Novel polymethine dyes and UV absorbers containing a triarylborylisocyano group and imaging compositions containing these dyes

ABSTRACT

Polymethine dyes and ultraviolet absorbers are disclosed containing a basic electron donating terminal nucleus and an acidic electron accepting terminal nucleus comprised of a triarylborylisocyano group. The dyes are useful in imaging materials.

FIELD OF THE INVENTION

This invention relates to polymethine dyes and ultraviolet absorbers andto imaging compositions and photographic elements containing these dyesand ultraviolet absorbers.

BACKGROUND OF THE INVENTION

Polymethine dyes and ultraviolet (UV) absorbers containing a chromophoreformed by an acidic electron accepting terminal nucleus and a basicelectron donating terminal nucleus joined through a methine chain arewell known. Such polymethines are commonly further categorized asmerocyanines, hemioxonols, or merostyryls.

In merocyanines the basic terminal nucleus is a heterocyclic nucleuscomprised of a five or six membered heterocyclic ring containing atleast one nitrogen heteroatom. To achieve significant light absorptionin the visible spectrum, thereby qualifying as a dye, the heterocyclicnucleus must exhibit aromaticity. In so-called zero methine merocyaninesthere are two methine groups linking the nuclei, but one linking methinegroup lies in the basic nucleus while the second linking methine grouplies in the acidic nucleus. Thus, there are no methine groups separatingthe nuclei. Homologues of the zero methine merocyanines are those whichcontain two, four, or a higher even number of methine groups joining theterminal acidic and basic nuclei.

Hemioxonals and merostyryls can be viewed as differing from merocyaninesin that their basic terminal nuclei take the form of aminomethine andp-aminophenylmethine nuclei, respectively.

The acidic electron accepting terminal nucleus of each of thesepolymethines can be either heterocyclic or acyclic. When the acidicterminal nucleus is acyclic, it takes the form of a methylene groupwhich is disubstitued with two strong electron withdrawing groups. Themost commonly employed strong electron withdrawing groups are cyano,sulfo, and carbonyl groups, where the latter includes carboxylic acidand ester as well as acyl groups. Acrylic acidic electron acceptingterminal nuclei of polymethines are illustrated by

(R-1) Collins et al U.S. Pat. No. 2,411,507,

(R-2) Kendall et al U.S. Pat. No. 2,511,210,

(R-3) Kendall et al U.S. Pat. No. 2,693,472,

(R-4) Edwards et al U.S. Pat. No. 2,721,799,

(R-5) Kofron et al U.S. Pat. No. 4,439,520, and

(R-6) Gunther et al U.S. Pat. No. 4,576,905.

Polymethines with a basic electron donating terminal nucleus and anacidic terminal nucleus are known to serve a variety of uses. Suchpolymethines are known to be useful both as UV absorbers and dyes. Thesedyes and UV absorbers have been incorporated into photographic elementsto serve a variety of purposes. In one application of particularinterest these polymethines are incorporated in ultraviolet responsiveimaging systems. Since ultraviolet light is both more energetic andcapable of absorption with simpler molecular resonance structures thanvisible light, it is not surprising that there are a variety of knownimaging materials which respond to ultraviolet, but not visible light.The sensitivity of these imaging systems can be extended to longerwavelength UV radiation and into the visible portion of the spectrum byincorporating a photosensitizer. Merocyanines have been extensivelyemployed as photosensitizers and to a lesser extent (largely due toshorter wavelength absorption peaks) hemioxonols and merostyryls havebeen similarly employed.

Photographic silver halide emulsions are illustrative of imaging systemsknown to employ dyes from these polymethine classes as photosensitizers.The radiation sensitive silver halide grains present in photographicemulsions exhibit very limited absorption of radiation of wavelengthsextending into the visible spectrum. However, with a dye absorbed to thegrain surfaces, the emulsions are highly responsive to visible light.The dye absorbs exposing photons and transfers either energy or anelectron to the grain. The patents cited above disclose thisphotographic utility for merocyanine, hemioxonol, and merostyryl dyes.

A variety of photographic imaging systems are known wherein a hardenableorganic component containing ethylenic unsaturation sites is relied uponfor image formation. The organic component undergoes photoinducedaddition reactions, typically either polymerization or crosslinking, atthe ethylenic unsaturation sites which produce hardening and allow imagediscrimination to be achieved.

It is common practice in preparing these compositions to employcoinitiators. One of the coinitiators is a photosensitizer.Photosensitizers are relied upon to capture photons of exposingradiation. The remaining coinitiator is referred to as an activator. Theactivator is not relied upon to respond directly to exposing radiation,but rather adjacent activator and photosensitizer molecules react,following excitation of the latter by photon capture, causing release bythe activator of a free radical which in turn induces immobilizingaddition reactions at sites of ethylenic unsaturation. The use ofmerocyanine dyes and UV absorbers as photosensitizers in such imagingsystems is illustrated by (R-7) Specht et al U.K. No. 3,083,832A.

(R-8) Research Disclosure, Vol. 200, December 1980, Item 20036,

while the use of a much wider variety of polymethine dyes asphotosensitizers in such imaging systems are disclosed by the followingfour commonly assigned copending patent applications: (A) Farid et alU.S. Ser. No. 933,712, filed Nov. 21, 1986, titled DYE SENSITIZEDPHOTOGRAPHIC IMAGING SYSTEM;

(B) Farid et al U.S. Ser. No. 933,658, filed Nov. 21, 1986, titledNEGATIVE WORKING PHOTORESISTS RESPONSIVE TO SHORTER VISIBLE WAVELENGTHSAND NOVEL COATED ARTICLES

(C) Farid et al U.S. Ser. No. 933,660, filed Nov. 21, 1986, titledNEGATIVE WORKING PHOTORESISTS RESPONSIVE TO LONGER VISIBLE WAVELENGTHSAND NOVEL COATED ARTICLES

(D) Farid et al U.S. Ser. No. 933,657, filed Nov. 21, 1986, titledENHANCED IMAGING COMPOSITION CONTAINING AN AZINIUM ACTIVATOR

The polymethines of this invention are produced by first synthesizingcorresponding polymethines containing an isocyano group as a part of theacidic terminal nucleus. The synthesis of merocyanine dyes containingsuch as isocyano group is the subject of commonly assigned, concurrentlyfiled patent application Ser. No. 67,843, titled NOVEL MEROCYANINE DYESAND IMAGING COMPOSITIONS.

The following illustrate known compounds containing isocyano groups:

(R-9) U. Schollkopf, "Recent Applications of α-Metalated Isocyanides inOrganic Synthesis", Angew. Chem., Int. End., 1977, 16, 339-422. Noteparticularly compounds 9, 16, 17a, 17b, 18, 19, 32, and 34.

(R-10) R. H. Hall et al, "Synthesis of C-Glycosyl Compounds. Part 1.Reaction of Ethylisocyanoacetate with2,3,5,6-Di-O-isopropylidene-D-mannono-1,4-lactone", J. Chem. Soc.,Perkin Trans. 1, 1977, 743-753. Note particularly compounds 6, 7, 11,and 12.

(R-11) C. Herdeis et al, "Heterocyclic Substituted Amino Acids viaα,β-Dehydroamino Acid Derivatives. Studies on Amino Acids",Heterocycles, 1983, 20, 2163-2167. Note particularly compounds 3a and3b.

(R-12) C. Herdeis et al, "Platin(II)-Komplexe Von VinylogenAminoisocyanides", Chem. Ber., 1983, 116, 3205-3211. Note particularlycompounds 1a and 1c.

(R-13) Schollkopf et al, "Syntheses with α-Metalated Isocyanides, XLIV.Note on β-Dimethylamino-α-isocyanoacrylates and Their Use inHeterocyclic Chemistry", Justus Liebigs Ann. Chem., 1979, 1444-6. Noteparticularly compound 3.

(R-14) Hoppe, "α-Metalated Isocyanides in Organic Synthesis", Angew.Chem., Int. Ed., 1974, 13, 789-804. More particularly compounds 143,145a, and 145b.

(R-15) I. Hoppe and U. Schollkopf, "Synthesis and Biological Activitiesof the Antibiotic B 371 and its Analogs", Justus Liebigs Ann. Chem.,1984, 600-607.

Compounds containing boron also containing an isonitrile group orprepared from a compound containing an isonitrile group are illustratedby the following:

(R-16) Ugi Isonitrile Chemistry, Chapter 6, "The Reaction of Isonitrileswith Boranes", Academic Press, 1971, New York and London.

SUMMARY OF THE INVENTION

In one aspect this invention is directed to a polymethine dye orultraviolet absorber containing a basic electron donating terminalnucleus joined through a methine linkage to an acidic electron acceptingterminal nucleus comprised of a triarylborylisocyano group.

In another aspect this invention is directed to an imaging compositioncomprised of an imaging material and a polymethine dye or ultravioletabsorber containing a basic electron donating terminal nucleus joinedthrough a methine linkage to an acidic electron accepting terminalnucleus comprised of a triarylborylisocyano group.

In still another aspect this invention is directed to a photographicelement comprised of a support and, coated on the support, one or morelayers including at least one radiation sensitive imaging layer, atleast one of the layers being comprised of a polymethine dye orultraviolet absorber containing a basic electron donating terminalnucleus joined through a methine linkage to an acidic electron acceptingterminal nucleus, characterized in that the acidic electron acceptingterminal nucleus is comprised of a triarylborylisocyano group.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is directed to and employs polymethine dyes andultraviolet (UV) absorbers differing from conventional polymethinescontaining a basic electron denoting terminal nucleus joined through amethine linkage to an acidic electron accepting terminal nucleus in thatthe latter nucleus is comprised of an triarylborylisocyano group. Theacidic electron accepting terminal nucleus of a polymethine dyeaccording to this invention can be represented in its extreme resonanceforms by the formulae: ##STR1## where Ar is independently in eachoccurrence an aromatic group and

D is a carbonyl, cyano, or sulfo group. Since the acidic nuclei ofpolymethines are usually depicted by formula and discussed in terms ofthe resonance form in which electron displacement to the acidic terminalnucleus has not occurred (the first of the two formulae above), thisestablished practice is followed in the subsequent discussion.

When D is a carbonyl group it can take the form of a carboxyl group,acyl group, or carboxylic ester group. It is therefore apparent that thecarbonyl group can be represented by the formulae --C(O)R and --C(O)OR,where R can take the form of hydrogen, a salt forming cation (e.g.,ammonium or alkali metal), or any convenient aliphatic or aromaticgroup. For example, R can be chosen from among alkyl and/or aryldisubstituted amino groups and alkyl, cycloalkyl, alkenyl, alkynyl,aryl, alkaryl, and aralkyl hydrocarbons. These hydrogen groups can befurther substituted, if desired. Typical substituents of the hydrocarboninclude oxy groups (e.g., alkoxy or aryloxy), thio groups (e.g.,alkylthio or arylthio), sulfonyl groups (e.g., alkylsulfonyl orarylsulfonyl), sulfo or sulfato (including a counterion, such ashydrogen or an alkali metal ion), amine, amino, amide, amido, carbamoyl,thioamido, thiocarbamoyl, ureido, thioureido, carbonyl (e.g., carboxyl,acyl, or carboxylic ester), and halogen. The alkyl moieties can bevaried widely in the number of carbon atoms contained. Alkyl, alkenyl,and alkynyl moieties of from 1 to 15 carbon atoms are specificallycontemplated, with 1 to 10 carbon atoms being preferred, and 1 to 6carbon atoms being generally optimum for use in polar solvents orhydrophilic media. Alkyl moieties of from 1 to 6 carbon atoms,hereinafter referred to as lower alkyl moieties, are most commonlyemployed. The aryl moieties are commonly limited to from 6 to 10 ringcarbon atoms to minimize molecular bulk. Phenyl and naphthyl are themost commonly employed aryl moieties; however, there is no reason inprinciple that other aromatic fused ring systems cannot be employed.

When D is a cyano (nitrilomethynyl) group, it can be represented by theformula --C.tbd.N. When D is a sulfo group, it can be represented by theformula --S(O)₂ R, where R can take any of the forms described above.

The aromatic group Ar can take the form of any convenient aromatic ringstructure. The aromatic ring structure is preferably an aromatic groupcontaining from 6 to 10 carbon atoms. Specifically preferred arecarbocyclic aromatic ring structures containing from 6 to 10 carbonatoms--e.g., phenyl, α-naphthyl, or β-naphthyl. Other carbocyclicaromatic ring structures are contemplated, such as anthracyl,phenanthracyl, and analogues having even larger numbers of fused rings,but such structures are generally less preferred, since they increasemolecular bulk without correspondingly increasing radiation absorption.The aromatic ring structures can be substituted, if desired, with any ofa variety of groups. For example, aromatic ring substituents can readilytake any of the various substituents of aryl groups described above inconnection with R. In order to append three separate aromaticsubstituents from a single boron atom steric compatibility must beconsidered in selecting substituents of the aryl groups. When the arylgroups are phenyl or β-naphthyl groups, no more than four ortho positionsubstituents are permissible, and these should be limited in molecularbulk--e.g. alkyl of from 1 to 3 carbon atoms or less bulky substituents.When the aryl groups are α-naphthyl and larger ring structures,substituents ortho to the ring bonding position should be avoided.

In addition to the acidic electron accepting terminal nucleus thepolymethines additionally include a basic electron donating terminalnucleus linked to the acidic nucleus through a carbon to carbon doublebond or intervening methine groups. The basic terminal nucleus and, whenpresent, the methine groups linking the basic and acidic terminal nucleican take any convenient form found in conventional polymethine dyes andUV absorbers.

In one preferred form the basic nucleus takes the form a heterocyclicnucleus comprised of a five or six membered heterocyclic ring containingat least one nitrogen heteroatom. When the basic nucleus takes this formthe polymethine is a merocyanine. In another preferred form the basicnucleus is an aminomethine group, and the resuling polymethine is ahemioxonol

Thus, the preferred polymethine dyes and UV. absorbers according to thepresent invention comprise those satifying the formulae: ##STR2## whereAr is independently in each occurrence an aromatic nucleus containingfrom 6 to 10 ring carbon atoms;

D is an electron withdrawing group having a cyano, sulfo, or carbonylgroup;

E is chosen from the class consisting of

(i) a heterocyclic nucleus comprised of a five or six memberedheterocyclic ring containing at least one heteroatom chosen from theclass consisting of nitrogen and chalcogen and

(ii) an aminomethine group;

L¹ and L² are methine groups; and

n is the integer 0, 1, or 2.

In one preferred form the heterocyclic nucleus E completes anazolinylidene or azinylidene ring. In the neutral and charged resonanceforms of the merocyanine dye the basic nucleus containing theazolinylidene or azinylidene ring can be represented by the formulae:##STR3## wherein p is the integer 0 or 1;

L³ and L⁴ independently represent methine groups;

R¹ is a quaternizing substituent; and

Q represents the atoms completing a basic azolinylidene or azinylidenenucleus.

In specifically preferred forms Q is chosen to complete an azolinylideneor azinylidene nucleus chosen from the group consisting of2-piperidylidene, 2-pyrrolidinylidene, 2- or 4-pyridylidene,imidazopyridylidene, 2- or 4-quinolinylidene, 1- or3-isoquinolinylidene, benzoquinolinylidene, thiazoloquinolylidene,imidazoquinolinylidene, 3H-indolylidene, 3H-benzindolylidene,oxazolinylidene, oxazolidinylidene, benzoxazolinylidene,naphthoxazolinylidene, oxadiazolinylidene, thiazolidinylidene,phenanthrothiazolinylidene, acenaphthothiazolinylidene,thiazolinylidene, benzothiazolinylidene, naphthothiazolinylidene,tetrahydrobenzothiazolinylidene, dihydronaphthothiazolinylidene,thiadioxazolinylidene, selenazolidinylidene, selenazolinylidene,benzoselenazolinylidene, naphthoselenazolinylidene,selenadiazolinylidene, benzotellurazolinylidene,naphthotelluroazolinylidene, pyrazolylidene, imidazolinylidene,imidazolidinylidene, benzimidazolinylidene, naphthimidazolinylidene,diazolinylidene, tetrazolinylidene, and imidazoquinoxalinylidene nuclei.

The quaternizing substituent (R¹) is an optionally substitutedhydrocarbon substituent, such as an alkyl, cycloalkyl, alkenyl, alkynyl,aryl, aralkyl, or alkaryl group. The number of carbon atoms in thehydrocarbon moieties as well as the various optional substitutents canbe chosen similarly as described above in connection with R.

In addition to azolinylidene and azinylidene nuclei, heterocyclicaromatic basic electron donating terminal nuclei satisfying therequirements of E in formulae II can be chosen from a variety of nucleiknown to form dyes which contain only chalogen heteroatoms. Such nucleiinclude pyranylidene, benzopyranylidene, dibenzopyranylidene,thiapyranylidene, benzothiapyranylidene, naphthothiapyranylidene,selenapyranylidene, tellurapyranylidene, benzotellurapyranylidene,naphthotellurapyranylidene, dithiolylidene (a.k.a. disulfolylidene),benzodithiolylidene, and naphthodithiolyidene nuclei. These nuclei aresimilar to the azolinylidene and azinylidene nuclei described above inthat they resonate between a form in which a ring heteroatom is chargedor uncharged, except that in these rings, no nitrogen atom beingpresent, it is a chalcogen atom which assumes a positive charge. In theresonance form in which the chalcogen atom is charged each pyranylidenenuclei is usually named as the corresponding pyrylium nucleus. Dyescontaining exemplary useful pyranylidene (i.e., pyrylium) nucleicontaining an oxygen, sulfur, selenium, or tellurium atom are disclosedin Detty et al U.S. Pat. Nos. 4,365,017 and 4,584,258.

When the polymethines of the invention are hemioxonols, E takes the forman aminomethine nucleus, which can be represented by the followingformulae: ##STR4## where L⁵ is methine group and

G and G¹ can independently take any of the forms of R and R¹ describedabove or can together complete a ring system derived from a cyclicsecondary amine, such as pyrrolidine, 3-pyrroline, piperidine,piperazine (e.g., 4-methylpiperazine and 4-phenylpiperazine),morpholine, 1,2,3,4-tetrahydroquinoline, decahydroquinoline,3-azabicyclo[3,2,2]nonane, indoline, azetidine, and hexahydroazepine.

The methine groups in formulae II, III, and IV--i.e., L¹, L², L³, L⁴,and L⁵, can be independently in each occurrence unsubstituted methinegroups (i.e., --CH═ groups) or substituted methine groups represented bythe formula --C(R²)═, where R² can represent any convenient monovalentsubstituent-- e.g., R² can take any of the various forms of R describedabove. Alkyl substituents of from 1 to 4 carbon atoms (e.g., methyl orethyl) and phenyl substituents (e.g., phenyl, tolyl, or xylyl) are mostcommonly encountered and are preferred. It is common to incorporate asubstituted methine in the methine linkage joining the terminal nucleito promote dye aggregation. In variant form R² in two different methinegroups can together take the form of an alkylene group of from 1 to 6carbon atoms. Such alkylene groups are referred to as bridging groupsand are commonly employed to rigidize the dye molecule.

When E takes the form of an aminomethine nucleus as represented byformula IV and L⁵ takes the form --C(R²)═, where R² is a secondary aminogroup, a preferred polymethine results satisfying the following formula:##STR5## where G² and G³ independently or together can take any of thevarious forms of G and G¹, G⁴ and G⁵ independently or together can takenany of the various forms of G and G¹, or G² and G⁴ can together completea 5 or 6 membered ring (e.g., an alkylene group providing 2 or 3 ringcarbon atoms joining the amino nitrogen atoms) and

Ar, D, L¹, L², and n can take any of the forms identified above.

Procedures for synthesizing representative polymethines according to theinventin are included in the examples below. From these examples thesynthesis of variant forms of the polymethines will be readily apparent.

Specific polymethines according to the invention are listed in Table I

                  TABLE I                                                         ______________________________________                                        D-1     Ethyl 4-(3-ethyl-2-benzothiazolinylidene)-2-                                  triphenylborylisocyano-2-butenoate                                    D-2     Ethyl 4-(3-ethyl-2-benzothiazolinylidene)-2-                                  tri( -p-fluorophenyl)borylisocyano-2-butenoate                        D-3     Ethyl 2-(3-ethyl-2-benzothiazolinylidene)-2-                                  triphenylborylisocyanoacetate                                         D-4     Ethyl 2-(3-ethyl-2-benzothiazolinylidene)-2-                                  tri( -p-fluorophenyl)borylisocyanate                                  D-5     Ethyl 6-(3-ethyl-2-benzothiazolinylidene)-2-                                  triphenylborylisocyano-2,4-hexadienoate                               D-6     Ethyl 6-(3-ethyl-2-benzothiazolinylidene)-2-                                  tri( -p-fluorophenyl)borylisocyano-2,4-hexadienoate                   D-7     3-Ethyl-2-(1-triphenylborylisocyano-1-phenyl-                                 sulfonyl-1-propen-3-ylidene)benzothiazoline                           D-8     Ethyl 4-(3-ethyl-2-benzoxazolinylidene)-2-tri-                                phenylborylisocyano-2-butenoate                                       D-9     Ethyl 4-(3-ethyl-2-benzoxazolinylidene)-2-tri-                                ( -p-fluorophenyl)borylisocyano-2-butenoate                           D-10    Ethyl 6-(3-ethyl-2-benzoxazolinylidene)-2-tri-                                phenylborylisocyano-2,4-hexadienoate                                  D-11    Ethyl 6-(3-ethyl-2-benzoxazolinylidene)-2-tri-                                ( -p-fluorophenyl)borylisocyano-2,4-hexadienoate                      D-12    2-[1-Cyano-1-tri( -p-fluorophenyl)borylisocyano-                              1-propen-3-ylidene]-3-ethylbenzoxazoline                              D-13    Ethyl 4-(3-ethyl-2-selenazolinylidene)-2-tri-                                 phenylborylisocyano-2-butenoate                                       D-14    Ethyl 4-(3-ethyl-2-benzoselenazolinylidene)-2-                                tri( -p-fluorophenyl)borylisocyano-2-butenoate                        D-15    Methyl 2-(3-ethyl-2-benzotellurazolinylidene)-                                2-triphenylborylisocyanoacetate                                       D-16    Ethyl 4-(1-ethyl-2-quinolinylidene)-2-tri-                                    phenylborylisocyano-2-butenoate                                       D-17    Ethyl 4-(1-ethyl-2-quinolinylidene)-2-tri( -p-                                fluorophenyl)borylisocyano-2-butenoate                                D-18    Methyl 4-(1-methyl-2-pyridylidene)-2-tri( -p-                                 fluorophenyl)borylisocyano-2-butenoate                                D-19    Ethyl 4-(5,6-dichloro-1,3-diethyl-2-benzimid- - azolinylidene)-2-t            riphenylborylisocyano-2-                                                      butenoate                                                             D-20    Ethyl 4-(5,6-dichloro-1,3-diethyl-2-benzimid-                                 azolinylidene)-2-tri( -p-fluorophenyl)boryl-                                  isocyano-2-butenoate                                                  D-21    Ethyl 4-[3,3-dimethyl-1-ethyl-2(3H)--indolyli-                                dene]-2-triphenylborylisocyano-2-butenoate                            D-22    Ethyl 2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-                               2-ylidene)-2-triphenylborylisocyanoacetate                            D-23    Ethyl 2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-                               2-ylidene)-2-tri( -p-fluorophenyl)borylisocyano-                              acetate                                                               D-24    Ethyl 4-(4,6-diphenyl-2-pyranylidene)-2-tri-                                  phenylborylisocyano-2-butenoate                                       D-25    Ethyl 4-(4,6-diphenyl-2-pyranylidene)-2-tri( -p-                              fluorophenyl)borylisocyano-2-butenoate                                D-26    Ethyl 4-(2,6-di- .sub.-t-butyl-4-selenapyranylidene)-                         2-tri( -p-fluorophenyl)borylisocyano-2-butenoate                      D-27    Ethyl 2-(2,6-diphenyl-4-tellurapyranylidene)-2-                               triphenylborylisocyanoacetate                                         D-28    Ethyl 4-(2-phenyl-4-benzothiapyranylidene)-2-                                 tri( -p-fluorophenyl)borylisocyano-2-butenoate                        D-29    Ethyl 4-(2,6-diphenyl-4-pyranylidene)-2-tri-                                  phenylborylisocyano-2-butenoate                                       D-30    Ethyl 4-(2,6-diphenyl-4-pyranylidene)-2-tri-                                  ( -p-fluorophenyl)borylisocyano-2-butenoate                           D-31    Ethyl 4-(1-ethyl-4-quinolinylidene)-2-tri-                                    phenylborylisocyano-2-butenoate                                       D-32    Ethyl 4-(1-ethyl-4-quinolinylidene)-2-tri( -p-                                fluorophenyl)borylisocyano-2-butenoate                                D-33    Ethyl 3-dimethylamino-2-triphenylborylisocyano-                               2-propenoate                                                          D-34    Ethyl 3-dimethylamino-2-tri( -p-fluorophenyl)-                                borylisocyano-2-propenoate                                            D-35    Methyl 3-dimethylamino-2-tri( -p-tolyl)boryliso-                              cyano-2-propenoate                                                    D-36    Ethyl 3,3-bis(dimethylamino)-2-triphenylboryl-                                isocyano-2-propenoate                                                 D-37    Ethyl 3,3-bis(dimethylamino)-2-tri( -p-fluoro-                                phenyl)borylisocyano-2-propenoate                                     D-38    Methyl 5-dimethylamino-2-triphenylboryliso-                                   cyano-2,4-pentadienoate                                               D-39    Ethyl 2-(1,3-dimethyl-2-imidazolidinylidene)-                                 2-triphenylborylisocyanoacetate                                       D-40    Ethyl 2-(1,3-dimethyl-2-oimidazolidinylidene)-                                2-tri( -p-fluorophenyl)borylisocyanoacetate                           ______________________________________                                    

The polymethine dyes and UV absorbers of this invention can serve any ofthe known uses for corresponding conventional polymethine dyes and UVabsorbers. Polymethine dyes have found extenive use in photography. Thepolymethines of this invention are specifically contemplated to be usedas photosensitizers in photographic imaging systems.

In one specific form a photographic imaging system according to thepresent invention containing a polymethine satisfying formulae II abovecan take the form of a silver halide photographic element. In its mostwidely employed form silver halide photography employes for imagingradiation sensitive silver halide grains. The grains are suspended in adispersing medium, typically including a hydrophilic colloid, such asgelatin, so that the grains and dispersing medium together form aradiation sensitive silver halide emulsion. The silver halide emulsionsare typically coated on a photographic film or paper support to form aphotographic element. A simple photographic element can consist of asupport and an emulsion layer; however, typically additional hydrophiliccolloid layers, such as multiple emulsion layers, subbing layers,interlayers, and overcoats are also present. The silver halide emulsionscan be usefully, though incompletely, categorized as those which formpredominatly surface or predominantly internal latent images uponexposure. Photographic elements can be conveniently classified as beingdirect positive photographic elements or negative working photographicelements. Whether a positive or negative viewable image is produced is afunction of both the emulsion chosen and the photographic processingundertaken. Although light processing is known and employed forspecialized applications, in most instances photographic processing toproduce a viewable image is accomplished by development of an imagewiseexposed photographic element in an aqueous alkaline processing solution.Usually internal latent image forming emulsions are employed incombination with uniform light exposure or, preferably a nucleatingagent, to produce direct positive images. Direct positive images can beproduced also by employing initially surface fogged silver halide grainswhich rely on selective development of unexposed grains to producedirect positive images. Internal latent image emulsions can be used toproduce negative images by internal development--that is, developing inthe presence of iodide ion or a silver halide solvent capable ofrendering the internal latent image site accessible to the developingagent. Aside from solarization effects, surface latent image emulsionscannot produce direct positive images, but are extensively used toproduce positive color images by reversal processing. Of extremeimportance to obtaining commercially attractive photographic images area large variety of emulsion, photographic element, and processingsolution addenda. A succinct summary of radiation sensitive silverhalide emulsions, photographic elements, processing solutions, theirbasic and modifying components, and significant patents and publicationsdescribing their features is contained in Research Disclosure, Vol. 176,December 1978, Item 17643. Research Disclosure is published by KennethMason Publications, Ltd., 8 North Street, Emsworth, Hampshire PO10 7DD,England.

The polymethines of this invention are in a preferred applicationincorporated into one or more hydrophilic colloid layers of silverhalide photographic elements. The location and concentration thepolymethine is dictated by the photograhically useful function sought tobe realized. The polymethine dyes of the invention can be located behindone or more silver halide emulsion layers as imagewise exposed to absorbactinic radiation penetrating the silver halide emulsion layer orlayers, thereby reducing scattered radiation. In other words, the dyescan be employed as antihalation dyes. The polymethines can beincorporated in interlayers or in overcoats to function as filter dyesand UV absorbers. When used as UV absorbers in overcoat layers thepolymethines can protect dye images in the photographic elements fromfading. In a preferred application the polymethines can be incorporateddirectly in the silver halide emulsion. They can increase photographicsharpness by intercepting and absorbing actinic radiation that wouldotherwise be reflected between grains. In other words, the dyes can takethe form of inter-grain absorbers.

When the merocyanine dyes are employed as a photosensitizer in aphotographic silver halide emulsion, they are adsorbed to the surfacesof the radiation-sensitive silver halide grains. As is generally wellunderstood in the art, optimum photosensitization is achieved when thedye concentration is chosen to provide a monomolecular coverage of from25 to 100 percent of the silver halide grain surface, as disclosed, forexample, in West et al, "The Adsorption of Sensitizing Dyes inPhotographic Emulsions", Journal of Phys. Chem., Vol. 56, 1952, p. 1065;Spence et al, "Desensitization of Sensitizing Dyes", Journal of Physicaland Colloid Chemistry, Vol. 56, No. 6, June 1948, pp. 1090-1103; andGilman et al U.S. Pat. No. 3,979,213. Optimum dye concentration levelsof photosensitization can be chosen by procedures taught by Mees, Theoryof the Photographic Process, First Edition, pp. 1067-1069.

A variety of imaging systems are known which contain a compositioncapable of being hardened imagewise by ultraviolet exposure. Byincorporating a polymethine dye according to the present invention theseimaging systems can be made to respond to imagewise exposures within thenear ultraviolet and/or visible spectrum. Such systems embrace negativeworking photoresists, which are used primarily to define image patternsof protective layers. Such systems additionally embrace dye imagingsystems in which hardening controls the mobility of an image dye or dyeprecursor.

A typical hardenable imaging system which can be rendered responsive toradiation in the near UV or visible spectrum by incorporation of apolymethine according to this invention includes in addition to thepolymethine an organic component which undergoes photoinduced additionreactions, typically either polymerization or crosslinking, at theethylenic unsaturation sites which produce hardening and an activator.

The photosensitizer and activator together form coinitiators forhardening. The photosensitizer is relied upon for photon capture in thevisible spectrum. Adjacent activator and photosensitizer moleculesreact, following excitation of the latter by photon capture, causingrelease by the activator of a free radical which in turn inducesimmobilizing addition reactions at sites of ethylenic unsaturation.

Since interaction of the activator and photosensitizer are required forsuccessful visible imaging, it is apparent that the choice of thespecific merocyanine dye according to the invention chosen for use as aphotosensitizer is related to the specific choice of the activator.

In one specifically contempleted form of the invention the activator cantake the form of an azinium salt. The azinium salt activators employedin the imaging compositions of this invention can take any convenientform and can be chosen from among known azinium salt activators. Theazinium activators disclosed by Heseltine et al and Jenkins et al U.S.Pat. Nos. Re. 27,922 and Re. 27,925, Specht and Farid U.K. 3,083,832A,and Research Disclosure, Vol. 200, December 1980, Item 20036, citedabove, provide a variety of examples of useful azinium activators.

In addition to being a polymethine as previously defined, to be usefulas a photosensitizer in the present invention the polymethine mustexhibit a reduction potential which is at most 0.1 volt more positivethan the reduction potential of the azinium salt activator with which itis employed. Electron transfer from the photosensitizer to the activatoris efficiently achieved when the reduction potential of the longerwavelength dye is more negative than that of the photoactivator. Inaddition, when the reduction potentials of the photosensitizer andactivator are equal, energy transfer can still occur. Further, effectiveperformance has been observed when the reduction potential of thephotosensitizer is more positive than that of the activator to a limiteddegree.

In the overwhelming majority of instances precise determinations ofreduction potentials are not required to ascertain that the properrelationship of reduction potentials of the azinium activator and thepolymethine exists. In those few instances in which the reductionpotential of the dye is sufficiently positive with respect to that ofthe activator that a precise determination of reduction potentials isdesired, it must be taken into account that reduction potentials canvary as a function of the manner in which they are measured. To providea specific standard for reduction potential determination, the procedureis employed described by J. Lenhard, "Measurement of ReversibleElectrode Potentials for Cyanine Dyes by the Use of Phase-SelectiveSecond Harmonic AC Voltammetry", Journal of Imaging Science, Vol. 30,No. 1, January/February 1986.

The remaining essential ingredient of the coinitiator containing imagingcomposition is an organic component containing ethylenic unsaturationsites and capable of selective hardening by addition at the sites ofethylenic unsaturation. A broad variety of vinyl monomers, vinyloligomers, and polymers containing ethylenic unsaturation are known anduseful in imaging systems according to the invention. Specific choicesof hardenable organic components are illustrated by reference to certainpreferred imaging systems.

In one preferred form of the invention the imaging composition can takethe form of a negative working photoresist. The organic component of thenegative-working photoresist to be acted upon by the coinitiators cantake the form of any conventional negative-working photoresist organicfilm forming component containing ethylenic unsaturation and capable ofselective immobilization by undergoing a hardening addition reaction atthe site of the ethylenic unsaturation. Immobilization can be impartedby initiating polymerization of monomers containing ethylenicunsaturation or by initiating crosslinking of linear polymers oroligomers containing ethylenic unsaturation. For example, any of themonomeric or crosslinkable polymeric film forming components disclosedin Jenkins et al and Heseltine et al U.S. Pat. Nos. Re. 27,925 or Re.27,922, respectively, are suitable for use in the imaging compositionsof this invention and are here incorporated by reference. Tan et al U.S.Pat. No. 4,289,842, here incorporated by reference, discloses negativeworking hardenable imaging compositions containing light sensitiveacrylate copolymers containing pendant groups, such as alkenyl groupwith ethylenic unsaturation. Lindley U.S. Pat. No. 4,590,147, hereincorporated by reference, discloses vinyl oligomers which can beemployed as film forming components in the hardenable imagingcompositions of this invention. Useful film forming componentscontaining vinyl monomers are diclosed in Fuerniss U.S. Pat. No.4,497,889 and Anderson et al U.S. Pat. No. 4,535,052, both hereincorporated by reference. Kosar Light-Sensitive Systems, John Wiley &Sons, 1965, further describes a variety of useful film formingcomponents for use in the practice of this invention, includingethylenically unsaturated monomers and polymers.

Preferred film forming components are comprised of at least one additionpolymerizable ethylenically unsaturated compound having a boiling pointabove 100° C. at normal pressure which is preferably employed incombination with a polymeric binder. The ethylenically unsaturatedcompound (typically a monomer) and the polymeric binder can be employedtogether in widely varying proportions, including ethylenicallyunsaturated compound ranging from 3 to 97 percent by weight of the filmforming component and polymeric binder ranging from 97 to 3 percent byweight of the film forming component. A separate polymeric binder,though preferred, is not an essential part of the film forming componentand is most commonly omitted when the ethenically unsaturated compoundis itself a polymer.

Chang U.S. Pat. No. 3,756,827, here incorporated by reference, disclosesin column 2, line 36 to column 3, line 30, a variety of suitable organicmonomers for use in the hardenable imaging compositions of thisinvention. Specifically illustrated in the examples below are estermonomers containing ethylenic unsaturation. Similar monomers includeethylenically unsaturated diester polyhydroxy polyethers, described inChambers U.S. Pat. No. 4,245,031, here incorporated by reference.

Organic polymeric binders which can form a part of the film formingcomponent of the photoresist include: (1) polyesters, including thosebased on terephthalic, isophthalic, sebacic, adipic, andhexahydroterephthalic acids; (2) nylons or polyamides; (3) celluloseethers and esters; (4) polyaldehydes; (5) high molecular weight ethyleneoxide polymers--e.g., poly(ethylene glycols), having weight averagemolecular weights from 4000 to 4,000,000; (6) polyurethanes; (7)polycarbonates; (8) synthetic rubbers--e.g., homopolymers and copolymersof butadienes, and (9) homopolymers and copolymers formed from monomerscontaining ethylenic unsaturation, such as polymerized forms of any ofthe various the ethylenically unsaturated monomers, such aspolyalkylenes--e.g. polyethylene and polypropylene; poly(vinyl alcohol);poly(vinyl esters)--e.g., poly(vinyl acetate); polystyrene; poly(acrylicand methacrylic acids and esters)--e.g., poly(methyl methacrylate) andpoly(ethyl acrylate), as well as copolymer variants.

The foregoing is, of course, only an illustrative listing of the mostcommonly encountered hardenable components. Other specific illustrativehardenable components are included in the examples.

In addition to the hardenable component and the coinitiators the imagingcompositions can contain any one or combination of known addenda, suchas thermal inhibitors, colorants (including dyes and pigments),plasticizers, fillers, etc. To facilitate coating on a substrate thefilm forming component, coinitiators, and addenda, if any, are usuallydispersed in a solvent to create a solution or slurry, the liquid beingevaporatively removed after coating. Any solvent can be employed forthis purpose which is inert toward the film forming components andaddenda of the photoresist. Solvents can be chosen from among a widevariety of organic liquids, including N,N-dimethylformamide;N,N-dimethylacetamide; alcohols, such as methanol, ethanol, butanol,etc.; ketones, such as acetone, cyclohexanone, and butanone; esters,such as ethyl acetate and ethyl benzoate; ethers, such astetrahydrofuran and dioxane; chlorinated aliphatic hydrocarbons, such asmethylene chloride and 1,2-dishloroethane; aromatic hydrocarbons, suchas benzene and toluene; and other common solvents, such as dimethylsulfoxide, chlorobenzene, and various mixtures of solvents.

The substrate onto which the photoresist is coated can take anyconvenient conventional form. For example, the photoresist can be usedto define a pattern during fabrication of an electronic component. Inthis instance the substrate can take the form of a printed circuit boardor semiconductor chip, typically one which has been only partiallyfabricated to a completed form. In other instances hardenable imagingcompositions can be coated on simple unitary substrates, such as glass,ceramic, metal, cellulose paper, fiberboard, or polymer substrates.Specific substrates include alumina-blasted aluminum, anodized aluminum,alumina-blasted poly(ethylene terephthalate) film, poly(ethyleneterephthalate) film, flame or electrostatic discharge treatedpoly(ethylene terephthalate) film, poly(vinyl alcohol)-coated paper,crosslinked polyester-coated paper, nylon, glass, cellulsoe acetate filmheavy paper, such as lithographic paper, and the like.

In perhaps their most commonly used form hardenable imaging compositionsare coated in a fluid form on a substrate and evaporatively dried,usually with heating, to produce a uniform coating. Often, particularlyin the manufacture of semiconductor devices, the substrate is spun,thereby employing cetrifugal forces to assure the uniformity of thephotoresist coating before drying. After exposure to actinic radiationcauses addition to occur at the ethylenic unsaturation sites of the filmforming component, a liquid developer is brought into contact with thecoated substrate to remove selectively the photoresist in areas whichwere not exposed to actinic radiation.

The liquid developer can be any convenient liquid which is capable ofselectively removing the photoresist in unexposed areas. The coatedphotoresist can be sprayed, flushed, swabbed, soaked, or otherwisetreated with the develope to achieve selective removal. In its simplestform the liquid developer can be the same liquid employed as a solventin coating the photoresist. Methoxethyl acetate and ethoxyethyl acetateare common developers. Also aqueous developers are commonly employed,such as miscible combinations of water and alcohols, with proportions inthe range of from 20 to 80 percent water and 80 to 20 percent alcoholbeing common. Exemplary water miscible alcohols include glycerol, benzylalcohol, 1,2-propanediol, sec-butyl alcohol, and ethers derived fromglycols, such as dihydroxy poly(alkylene oxides). Lactone developers,such as those disclosed by Martinson et al U.S. Pat. No. 3,707,373, canbe employed. Optimum developer choices for specific hardenable imagingcompositions are disclosed in the various patents cited aboveillustrating the specific film forming components.

In another manner of use, a photoresist layer is coated on a support andovercoated with a strippable cover sheet. The end user typicallypurchases the photoresist as an article rather than a liquidcomposition. After removing the cover sheet, the photoresist layertogether with its support is laminated to the substrate on which theimage pattern is desired. Following patterned exposure to actinicradiation through the support, the support is stripped from thesubstrate leaving photoresist on the substrate in an imagewise pattern.

In still another manner of use the photoresist is coated on a supportsurface modified to facilitate electroless metal deposition. Again, astrippable cover sheet is located on the photoresist coating. In thisuse imagewise exposure to actinic radiation occurs through the coversheet followed by stripping. Upon stripping of the cover sheet there isselective removal of the photoresist so that remaining photoresistdefines the desired pattern. Electroless metal plating can then beundertaken to convert the support into an article having a metal patternthereon. A common application is in the formation of electricalcircuits.

Any conventional ratio of activator to film forming component can bepresent in the hardenable imaging compositions of this invention.Activator concentrations are as a practical matter most convenientlyspecified in terms of moles of activator per gram of dry solids, thelatter consisting of the film forming component and the minor amounts ofvarious addenda, but excluding any liquid component introduced tofacilitate coating. Typically from about 2×10⁻⁵ to 25×10⁻⁵, mostpreferably from about 5×10⁻⁵ to 20×10⁻⁵ mole of activator is present pergram of dry solids.

The photosensitizer can be present in any concentration capable ofincreasing the response of the photoresist to ultraviolet or visiblelight. While the photosensitizer concentration can vary widely, it isgenerally contemplated to employ photosensitizer in concentrationsranging from about 5×10⁻⁷ to 1×10⁻⁴ mole per gram of dry solids.Preferred photosensitizer concentrations are in the range of from 10⁻⁶to 5×10⁻⁵ mole per gram of dry solids, with optimum concentrationsgenerally being in the range of from about 2×10⁻⁶ to 2×10⁻⁵ mole pergram of dry solids.

It is possible to employ the various photoresists described above toform either monochromic or multicolor dye images merely by incorporatingan imaging dye or dye precursor in the photoresist composition.Following development of the photoresist a retained dye image ispresented by the photoresist coating remaining on the substrate. Thecolored areas correspond to the areas of exposure. Multicolor images,such as images employed for color proofing, can be produced bysuperimposing three elements each comprised of a transparent support anda photoresist image, where each image is formed by a different additiveor subtractive primary dye.

In the foregoing imaging systems only a single coated layer is requiredfor imaging. However, it is recognized that the imagining systems of theinvention can employ multiple layers. For example, instead of blendingthe imaging dye with the film forming component as described above, aseparate imaging dye layer can be coated between the substrate and thephotoresist layer. Upon imagewise exposure and development thephotoresist is removed in exposed areas. Where the photoresist remainsthe underlying image dye remains in its initial immobilized condition,while in other areas the dye can be removed or decolorized by washing orany other convenient technique.

In the foregoing description of photoresists the hardenable organiccomponent containing ethylenic unsaturation sites is a film formingcomponent. However, in certain preferred imaging systems of theinvention the hardenable organic component can be present as adiscontinuous or internal phase forming microcapsules which can be incontact with a surrounding continuous phase or separated therefrom byintervening rupturable encapsulating walls. While it is possible to coatmicrocapsules each containing the hardenable organic component,coinitiators, and imaging dye or dye precursor to form a single colorimage, the present invention makes possible the formation of multicolorimages employing a single layer of microcapsules coated on a support.Since the microcapsules form discrete packets of materials, it ispossible to mix in the same layer microcapsules containing dyephotosensitizers which absorb at differing locations in the visiblespectrum and imaging dyes (or their precursors) of differing imaginghues. For example, it is contemplated to coat as a single layer on asubstrate (a) microcapsules containing a yellow dye photosensitizer anda yellow or blue imaging dye or its precursor, (b) microcapsulescontaining a magenta dye photosensitizer and a magenta or green imagingdye or its precursor, and (c) microcapsules containing a cyan dyephotosensitizer and a cyan or red imaging dye or its precursor. Exceptfor the choice of dye photosensitizer and imaging dye the microcapsulescan be otherwise identical. Thus, merely by blending three differingpopulations of microcapsules it is possible to obtain multicolor imageswith the same ease and facility as monochromic dye images are obtained.Excpet for hue selection of components and blending of microcapsulepopluations prior to coating, monochromic and multicolor imagingaccording to this invention are indentical. Therefore, for simplicitythe description which follows is in terms of monochromic imaging, butthe description is applicable to both monochromic and multicolorimaging, except as specifically noted.

The microcapsules can be employed to produce either a retained or atransferred dye image. Further, either a preformed dye or, preferably, adye precursor can be contained in the microcapsules.

In the retained imaging system a receiver layer is coated on a substrateand is overcoated by a layer of microcapsules. Within each coatedmicrocapsule exposure to light which is absorbed by the dyephotosensitizer results in release of a free radical by the aziniumactivator which in turn results in hardening of the organic componentcontaining ethylenic unsaturation. Subsequent uniform rupture of all thecoated microcapsules, as by passing the exposed element between pressurerollers, results in migration of imaging dye or its precursor from themicrocapsules which were not exposed and hence were not internallyhardened.

The released dye or dye precursor diffuses into the receiver layer.Where an imaging dye is contained in the microcapsules, the receiverlayer can be formed of any convenient transparent dye penetrablematerial. For example, the dye can enter a hydrophilic colloid layer orfilm forming polymer layer. Preferably a mordant is present in thereceiver layer to immobilize the image dye on receipt.

When the microcapsules contain a dye precursor, the dye image forminglayer contains a second component capable of interacting with the dyeprecursor to form the image dye. One of the two components ishereinafter referred to as a chromogenic material and the other isreferred to as a developer. Either or both can be viewed as a dyeprecursor and either can be located within the microcapsules with theother located in the dye image forming layer in monochromic imaging.However, for multicolor imaging the chromogenic materials, which differbased on the hue of the dye to be produced, are located within themicrocapsules. For simplicity subsequent discussion is directed tochromogenic materials contained in the microcapsules with developerbeing located in the receiver layer, but the converse arrangement ispossible, except as specifically noted. The receiver layer can besimilar to the receiver for a preformed imaging dye, differing only bythe additional inclusion of a developer.

Transferred dye image systems can be similar to the retained dye imagesystems described above, but differ in the location of the receiverlayer. Instead of coating the receiver layer on the same support as themicrocapsules, the receiver layer is coated on a separate support. Inintegral format arrangements the receiver layer and its support can beassociated with the microcapsule layer and its support at the time ofexposure as well as at the time transfer to the receiver from themicrocapsules occurs. Alternatively, the receiver layer and its supportneed not be associated with the microcapsule layer until rupture of themicrocapsules occurs. In either arrangement the receiver layer and itssupport can be employed alone as the image bearing element or can beretained with the microcapsule layer and its support. In the latterinstance the photobleachability of the photosensitizer and the initiallycolorless form of the chromogenic material are particularlyadvantageous.

In general similar materials can be employed in forming the microcapsulesystems described above as have been previously described in connectionwith negative-working photoresists, the principal difference being inthe physical continuity of the imaging layer. However, certain materialsdescribed below have been found to be particularly well suited to use inmicrocapsule imaging systems and constitute preferred materials.

Preferred hardenable organic components containing ethylenicunsaturation include compounds containing at least one terminalethylenic group per molecule and preferably two or more terminalethylenic groups per molecule. Typically they are liquid and can alsodouble as a carrier oil for the chromogenic material in the internalphase. Representative examples of these compounds include ethylenicallyunsaturated acid esters of polyhydric alcohols such as trimethylolpropane triacrylate. Another preferred hardenable component can includean acrylate prepolymer derived from the partial reaction ofpentaerythritrol with acrylic acid or acrylic acid esters. Suchmaterials are available from Richardson Company, Melrose Park,Ill.--e.g., Rl-1482 and Rl-1483. Also useful are isocyanate modifiedacrylate, methacrylate, and itaconic acid esters of polyhydric alcohols,such as disclosed by Carlick et al U.S. Pat. Nos. 3,825,479; 3,759,809;and 3,783,151.

The chromogenic materials used in the present invention are preferablyoil soluble color formers which produce a dye upon reaction with adeveloper in the presence of a carrier oil. Representative examples ofsuch chromogenic materials include substantially colorless compoundsincluding a lactone, lactam, sultone, spiropyran, ester, or amidostructure. Specifically preferred chromogenic materials aretriarylmethane, bisphenylmethane, xanthene, thiazine, spiropyran, andsimilar compounds. Also useful as chromogenic materials are organiccompounds capable of complexing with heavy metals to form dyes--e.g.,copper phthalocyanine. Specific additive and substractive dye formingchromogenic materials are disclosed in U.S. Pat. Nos. 3,920,510;4,399,209; and 4,440,846, here incorporated by reference.

In addition to the hardenable organic component, the coinitiators, andthe chromogenic material, the discrete phase or microcapsules can alsocontain a carrier oil. Preferred carrier oils are weakly polar solventshaving boiling points above 170° C. and preferably in the range of from180° C. to 300° C. Exemplary carrier oils include alkylated biphenyls(e.g., monoisopropylbiphenyl), polychorinated biphenyls, caster oil,mineral oil, deodorized kerosene, naphthenic mineral oils, dibutylphthalate, dibutyl fumerate, brominated paraffin, and mixtures thereof.Alkylated biphenyls are preferred on the basis of low toxicity whilebrominated paraffins employed in combination with trimethylol propanetriacrylate are particularly preferred for halftone imaging.

Carrier oils are not required. As previously noted the hardenableorganic component can in many instances perform the mobility providingfunction of a carrier oil, particularly where the hardenable organiccomponent is a monomer. The choice of carrier oil will depend to someextent on the chromogenic material to be transported on rupture of themicrocapsule. Carrier oils are chosen on the basis of their ability toimpart mobility to the chromogenic material in the absence of hardeningof the organic component containing ethylenic unsaturation as well asbeing nonreactive with the various components of the microcapsules.

The internal phase forming the microcapsules is then comprises of thehardenable organic component, an optical carrier oil, a chromogenicmaterial, coinitiator, and any of a variety of optional componentsintended to offer improvement in imaging properties, such as lightscattering materials, stabilizers, and the like.

The materials forming the internal phase of the microcapsules can bepresent in generally similar concentration ranges as previouslydescribed in connection with photoresists. In general the hardenableorganic component constitutes at least about 40 percent by weight of theinternal phase and typically constitutes from about 50 to 99 percent byweight of the internal phase. The chromogenic material can be present inany concentration compatible with providing a visible dye image. Ingeneral useful concentrations range from about 0.5 to 20.0 percent byweight, based on the weight of the internal phase. A preferred range ofchromogenic material for monochromic imaging is from about 2 to 7percent by weight of the internal phase. In multicolor imaging asomewhat higher concentration of chromogenic material is preferred,since only a third of the microcapsules are available to provide amaximum image dye density of any primary hue. For example, a maximumdensity magenta image must be formed using only the one third of themicrocapsules containing the chromogenic material which forms a magentadye. A preferred range of chromogenic material for multicolor imaging isfrom about 5 to 15 percent by weight of the internal phase. Carrier oilsare not required, but can be present in concentrations of up to about 50percent by weight of the internal phase, preferably in concentrations offrom about 10 to 40 percent of the internal phase. The coinitiators canbe present in the same concentrations set out above for thephotoresists, where the dye solids percentage bases corresponds tointernal phase percentage bases for the microcapsule utility.

In preferred forms the microcapsules each include in addition to theinternal phase a rupturable surrounding encapsulating wall.Encapsulation can be undertaken in any conventional manner. Oil solublechromogenic materials have been encapsulated in hydrophilic wall formingmaterials, such as gelatin and gelatin derivatives (e.g., phthalatedgelatin), gum arabic, polyvinyl alcohol, and carboxymethylcellulose wallforming materials, as illustrated by Green et al U.S. Pat. Nos.2,730,456 and 2,800,457; resorcinol-formaldehyde wall formers, asillustrated by Vassiliades U.S. Pat. No. 3,914,511; isocyanate-polyolwall formers, as illustrated by Kiritani et al U.S. Pat. No. 3,796,669;urea-formaldehyde wall formers, particularlyurea-resorcinol-formaldehyde wall formers, as illustrated by Foris et alU.S. Pat. Nos. 4,001,140, 4,087,376, and 4,089,802;melamine-formaldehyde resin wall formers; and hydroxypropyl cellulosewall formers, as illustrated by Shackle U.S. Pat. No. 4,025,455; all ofthe foregoing patents being here incorporated by reference. The wallformers must, of course, be capable of transmitting exposing radiation.Preferred wall formers are gelatin and gelatin derivatives as well asurea-resorsinol-formaldehyde wall formers. Microencapsulation can beaccomplished by any convenient conventional technique, includingcoacervation, interfacial polymerization, polymerization of one or moremonomers in oil, as well as various melting dispersing, and coolingmethods.

The microcapsules normally are chosen to be of a size too small to beindividually discerned by the unaided eye. The microcapsules preferablyrange from about 1 to 25 micrometers (μm) in diameter, more typicallyfrom about 3 to 15 μm in diameter, depending upon the sharpness of theimage desired, the smoothness of the support surface, and the techniqueused for rupturing the microcapsules. Generally the sharpness of the dyeimage increases as the size of microcapsules decreases. However, smallermicrocapsules are less easily coated on rough surface supports and lesseasily ruptured uniformly by mechanical techniques.

The microcapsules are normally coated at a density sufficient to atleast cover the surface of the support. That is, based on the averagediameter of the microcapsules the coating coverage is chosen to provideat least a monolayer coverage of microcapsules on the support.

Instead of forming the microcapsules with discrete walls, it isappreciated that microcapsule containing compositions suitable forcoating on a substrate can be produced by forming an emulsion in whichthe microcapsules constitute the discontinuous or internal phase and abinder analogous to the wall formers above constitutes the continuousphase. For example, such microcapsule coatings can be formed employinghydrophilic binders, such as hardened gelatin and gelatin derivatives.

Reacting with the chromogenic material (or first dye precursor) is adeveloper (or second dye precursor). The developer can take the form ofany material capable of reacting with the chromogenic material toproduce a dye. For the preferred classes of chromogenic materialsidentified above illustrative developers include clay minerals, such asacid clay, and active clay attapulgite; organic acids such as tannicacid, gallic acid, and propyl gallate; acid polymers, such asphenol-formaldehyde resins; condensates of carboxylic acids containingat least one hydroxy group and formaldehyde; metal salts of aromaticcarboxylic acids, such as zinc salicylate, tin salicylate, zinc2-hydroxynaphthenoate, zinc 3,5-di-tert-butylsalicylate; oil solublemetal salts of phenol-formaldehyde novolak resins (more specificallyillustrated by U.S. Pat. Nos. 3,672,935; 3,732,120; and 3,737,410), zinccarbonate, and mixtures of the above.

When the developer is coated on a substrate, as is preferred, thedeveloper is typically dispersed in a binder. The binder is chosen to berelatively dye permeable inert material, such as poly(vinyl alcohol),gelatin or a gelatin derivative, maleic anhydride-styrene copolymer,starch, gum arabic, or a cellulose ester. In general well known filmforming binders are useful. As mentioned above, a mordant can beincorporated in the binder for the developer to assist in immobilizingthe dye once it is formed. A variety of mordants particularly compatiblewith gelatin and gelatin derivatives are disclosed by Hartman U.S. Pat.No. 4,315,978.

While the microcapsule containing imaging system has been describedabove in terms of employing a chromogenic material and a developer, itis appreciated that mobile imaging dyes can be substituted for the thechromogenic material, if desired. The advantage of employing chromogenicmaterials is that the chromogenic material need contain no chromophoreto compete with the photosensitizer for photon dye capture. Further, thechromogenic material minimizes coloration of the imaging system in areaswhere no image dye is formed.

While the preferred microcapsule imaging systems above have beendescribed in terms of forming a discontinuous oleophilic phase in acontinuous hydrophilic phase, it is appreciated that the reverserelationship is also possible. It is specifically contemplated to formmicrocapsules containing dyes or chromogenic materials which are morehydrophilic and to rely on the relative hydrophobicity if notimpermeability of the microcapsule walls to initially confine the dyes.Where microcapsule wall formers are present, the same relativelyhydrophilic binders described above can still be employed. The importantpoint to note is that an extremely broad range of imaging dyes andchromogenic materials are available for use. Hartman U.S. Pat. No.4,315,978 illustrates a variety of yellow, magenta, and cyan dyescontaining polar substituents to impart mobility in more hydrophilicmedia.

While a few diverse imaging systems which constitute preferredembodiments of the invention have been specifically described, it isapparent that still other imaging systems employing an organic componentwhich is hardenable by addition at sites of ethylenic unsaturation canalso be improved by the incorporation of coinitiators as previouslydescribed.

EXAMPLES

The invention can be better appreciated by reference to the followingspecific examples.

EXAMPLE 1 Preparation of Ethyl4-(3-ethyl-2-benzothiazolinylidene)-2-triphenylborylisocyano-2-butenoate(D-1) (a) Preparation of Ethyl4-(3-ethyl-2-benzothiazolinyldene)-2-isocyano-2-butenoate (D-1a)

To a solution of potassium t-butoxide (3.05 g, 27.2 mmol) in dry,distilled tetrahydrofuran (70 mL) at -78° C. under argon was addeddropwise from an addition funnel a solution of ethyl isocyanoacetate(3.08 g, 27.2 mmol) in dry distilled tetrahydrofuran (30 mL). Theresulting thin, brown slurry was stirred 30 min at -78° C. Solid2-(2-acetanilidovinyl)-3-ethylbenzothiazolium iodide (12.3 g, 27.2 mmol)was added in one portion, and the reaction was allowed to warm toambient temperature and stir 16 hours. The reaction was poured onto 150mL water and 50 mL saturated aqueous ammonium chloride, and extractedthree times with ethyl acetate. The combined extracts were washed withwater and saturated sodium chloride, dried over sodium sulfate, andfiltered. The solvent was removed under reduced pressure.

The residue was triturated with absolute ethanol, and the resultingsolid was filtered, then recrystallized from absolute ethanol to give4.05 g (50%) D-1a as orange needles (mp 134°-135° C.).

¹ H NMR (300 MHz, CDCl₃) δ7.62 (1H, d, J=12.4), 7.47 (1H, d, J=7.7),7.36 (1H, t, J=7.8), 7.16 (1H, t, J=7.6), 7.06 (1H, d, J=8.2), 5.69 (1H,d, J=12.4), 4.30 (2H, q, J=7.1), 4.06 (2H, g, J=7.1), 1.42 (3H, t,J=7.1), 1.37 (3H, t, J=7.1), IR(KBr) 2105, 1690, 1595, 1565, 1535 cm⁻¹.FDMS (m/e) 300 (M+).

λ_(max) CH₂ Cl₂ (ε) 443 (62,000). Anal. calc'd. for C₁₆ H₁₆ N₂ O₂ S: C,64.0; H, 5.4; N, 9.3. Found: C, 63.9; H, 5.4; N, 9.3.

(b) Preparation of Product (D-1)

Triphenylborane (1.56 g, 6.45 mmol) was transferred to a 100 ml 2-neckflask in a glove bag under argon. Dry, distilled tetrahydrofuran (10 ml)was added, and the slurry was cooled to 0° C. under argon. A solution ofethyl 4-(3-ethyl-2-benzothiazolinylidene)-2-isocyano-2-butenoate (1.94g, 6.45 mmol) in dry, distilled tetrahydrofuran (10 ml) was transferredto the triphenylborane slurry through a cannula. The resulting thickorange slurry was allowed to warm to ambient temperature, and wasstirred 30 min. Diethyl ether (70 ml) was added, then the orange solidwas collected by filtration, washed with additional ether, and dried togive 2.79 g (80%) D-1. The filtrate was evaporated to dryness andtriturated with 1:1 ether:absolute ethanol. Filtration gave anadditional 0.40 g (11%) of D-1 (total crude yield: 91%). The crudematerial was homogeneous by thin layer chromatography and 300 MHz ¹ HNMR, and was used without purification for most purposes.

A portion was recrystallized from dichloromethane/ethanol to give D-1 asan orange, flaky solid (mp 160°-161° C. (dec.)).

¹ H NMR (300 MHz, CDCl₃) δ 7.81 (1H, d, J=13.0), 7.51 (1H, d, J=7.7),7.42-7.34 (7 H, m), 7.30-7.20 9H, M), 7.16 (1H, t, J=7.2), 7.10 (1H, d,J=8.2), 5.48 (1H, d, J=13.0), 4.29 (2H, q, J=7.1), 3.63 (2H, q, J=7.1),1.37 (3H, t, J=7.1), 1.10 (3H, t, J=7.1). IR (KBr) 1710, 1600, 1565,1530 cm⁻¹. FDMS (m/e) 542 (M+), 300.

λ_(max) CH₂ Cl₂ (ε) 462 (87,000). Anal. calc'd. for C₃₄ H₃₁ BN₂ O₂ S: C75.3; H, 5.8; N, 5.2. Found: C, 75.7; H, 5.9; N, 5.2.

EXAMPLE 2 Preparation ofEthyl-4-(3-ethyl-2-benzothiazolinyldene-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-2)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (1.91g, 6.47 mmol) in tetrahydrofuran (20 mL); and (2) ethyl4-(3-ethyl-2-benzothiazolinylidene)-2-isocyano-2-butenoate (D-1a) (1.94g, 6.47 mmol) in tetrahydrofuran (20 mL). After the reaction had stirred30 min at 0° C., the solvent was removed under reduced pressure and theresidue was triturated with ethanol (20 mL) with slight warming. Aftercooling, the resulting orange-yellow solid was collected by filtrationand dried (crude yield: 2.59 g). The material was recrystallized fromdichloromethane/ethanol, with filtration to remove insolubles, and theproduct D-2 was isolated as red-orange needles (2.30 g, 60%).

In a separate experiment as small portion was recrystallized fromethanol to give an orange flaky solid (mp 164°-166° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.87 (1H, d, J=13.0), 7.56 (1H, d, J=7.6),7.44 (1H, t, J=7.7), 7.27 (7H, m), 7.17 (1H, d, J=8.2), 6.97 (6H, app t,J=8.9), 5.40 1H, d, J=13.0), 4.33 (2H, q, J=7.1), 3.72 (2H, q, J=7.1),1.39 (3H, t, J=7.1), 1.16 (3H, t, J=7.1). IR (KBr) 1710, 1595, 1560,1525, 1475 cm⁻¹. FDMS (m/e) 596 (M+), 300, 296.

λ_(max) CH₂ Cl₂ (ε): 463 (86,000), 441 (52,000) (sh), 284 (11,000), 266(17,000). Anal. calc'd. for C₃₄ H₂₈ BF₃ N₂ O₂ S: C, 68.5; H, 4.7: N,4.7. Found: C, 68.3; H, 4.9; N, 4.6.

EXAMPLE 3 Preparation of Ethyl2-(3-ethyl-2-benzothiazolinylidene)-2-triphenylborylisocyanoacetate(D-3) (a) Preparation of Ethyl2-(3-ethyl-2-benzothiazolinylidene-2-isocyanoacetate (D-3a)

The same procedure was employed as for Example 1 (D-1a), but using3-ethyl-2-thiophenylbenzothiazolium iodide (10.9 g, 27.2 mmol) as thealkylating agent. The reaction was worked up as in Example 1, andtrituration of the crude product obtained after solvent evaporation gave3.91 g (52%) D-3a as a light solid that was pure by NMR and TLC (20/80ethyl acetate/cyclohexane).

A small portion was recrystallized from ethyl acetate/ethanol foranalysis and melting point (168.5°-171° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.54 (1H, d, J=7.8), 7.38 (1H, t, J=7.8),7.26-7.19 (2H, m), 4.59 (2H, q, J=7.1), 4.33 (2H, q, J=7.1), 1.58 (3H,t, J=7.1), 1.37 (3H, t, J=7.1). IR (KBr) 2090, 1665, 1510 cm⁻¹. FDMS(m/e) 274 (M+).

λ_(max) CH₂ Cl₂ (ε): 347 (39,000), 337 (32,000) (sh). Anal. calc'd forC₁₄ H₁₄ N₂ O₂ S: C, 61.3; H, 5.1; N, 10.2. Found: C, 61.7; H, 5.2; N,10.2.

(b) Preparation of Product (D-3)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylboron (1.51 g, 6.23mmol) in tetrahydrofuran (10 mL); and (2) ethyl2-(3-ethyl-2-benzothiazolinylidene)-2-isocyano-2-acetate (D-3a) (1.7 g,6.23 mmol) in tetrahydrofuran (10 mL). The resulting thick slurry wasstirred briefly at 0° C., then allowed to warm to ambient temperatureand stir for 30 min. The solvent was removed under reduced pressure andthe residue was triturated with ether (70 mL). The solid was collectedby filtration to give the product as an off-white flaky solid (2.79 g).The material was homogeneous by TLC and NMR.

A portion was recrystallized from dichloromethane/ethanol with a hotfiltration for analysis and mp (140°-142° C.).

¹ H NMR (300 MHz, CDCl₃), δ 7.62 (1H, d, J=7.8), 7.44-7.38 (7H, m),7.33-7.15 (11H, m), 4.40 (2H, q, J=7.1), 4.01 (2H, q, J=7.1), 1.40 (3H,t, J=7.1), 0.92 (3H, t, J=7.1). IR (KBr) 1680, 1510, 1470 cm⁻¹. FDMS(m/e) 516 (M+), 274, 242.

λ_(max) CH₂ Cl₂ (ε): 349 (46,000). Anal. calc'd. for C₃₂ H₂₉ BN₂ O₂ S:C, 74.4; H, 5.7; N, 5.4. Found: C, 74.7; H, 5.8; N, 5.4.

EXAMPLE 4 Preparation of Ethyl2-(3-ethyl-2-benzothiazolinylidene)-2-tri(-p-fluorophenyl)borylisocyanaoacetate(D-4)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (1.78g, 6.01 mmol) in tetrahydrofuran (10 mL); and (2) ethyl2-(3-ethyl-2-benzothiazolinylidene)-2-isocyanoacetate (D-3a) (1.65 g,6.01 mmol) in tetrahydrofuran (10 mL). The resulting dark solution wasstirred at 0° C. for 30 min, and the solvent was removed under reducedpressure. The residue was triturated with ethanol and the resultingoff-white solid was isolated by filtration (3.05 g, 89%).Recrystallization from a 1:1 mixture of ethyl acetate and ethanol gavethe pure product as light yellow needles (1.68 g, 49%). A second crop(0.93 g) consisted of a mixture of the desired product and arearrangement product.

In a separate experiment, recrystallization of the crude material fromethanol gave the pure product as a tan crystalline solid (mp 158°-160°C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.66 (1H, d, J=7.5), 7.47 (1H, t, J=7.6),7.38-7.22 (8H, m), 6.98 (6H, t, J=8.9), 4.41 (2H, q, J=7.1), 4.08 (2H,q, J=7.1), 1.39 (3H, t, J=7.1), 1.00 (3H, t, J=7.1). IR (KBr) 1690,1595, 1510, 1480 cm⁻¹. FDMS (m/e) 570 (M+), 296, 274.

λ_(max) CH₂ Cl₂ (ε): 349 (46,000). Anal. calc'd. for C₃₂ H₂₆ BF₃ N₂ O₂S: C, 67.4; H, 4.6; N, 4.9. Found: C, 67.0; H, 4.8; N, 4.8.

EXAMPLE 5 Preparation of Ethyl6-(3-ethyl-2-benzothiazolinylidene)-2-triphenylborylisocyano-2,4-hexadienoate(D-5) (a) Preparation of Ethyl6-(3-ethyl-2-benzothiazolinylidene)-2-isocyano-2,4-hexadienoate (D-5a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide (5.6g, 50 mmol) in tetrahydrofuran (120 mL); (2) ethyl isocyanoacetate (5.65g, 50 mmol) in tetrahydrofuran (40 mL); (3)2-(4-acetanilido-1-butadienyl)-3-ethylbenzothiazolium iodide (23.8 g, 50mmol). After the reaction was stirred at ambient temperature overnight,it was quenced with 1:3 saturated ammonium chloride/water and ethylacetate (200 mL), then was filtered to remove insolubles. The organiclayer was separated and the aqueous layer was extracted twice more withethyl acetate. The combined extracts were washed with saturated sodiumchloride and dried over sodium sulfate, then filtered. The solvent wasremoved under reduced pressure. The residue was triturated with 1:1ethyl acetate/ether to give 2.49 g (15% ) D-5a as a blue crystallinesolid that was homogeneous by TLC (2:8 ethyl acetate/cyclohexane).

In a different experiment, a small portion of crude material wasrecrystallized from ethanol to give D-5a (black needles) for analysisand melting point (163°-165° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.40 (1H, d, J=8.8), 7.39 (1H, d, J=11.2),7.28 (1H, t, J=7.9), 7.07 (1H, t, J=7.5), 6.97 (1H, dd, J=13.5, 12.2),6.94 (1H, d, J=7.9), 6.28 (1H, dd, J=13.5, 12.2), 5.67 (1H, d, J=11.8),4.27 (2H, q, J=7.1), 3.92 (2H, q, J=7.1), 1.35 (6H, 2 overlapping t). IR(KBr): 2100, 1705, 1570, 1500 cm⁻¹. FDMS (m/e) 326 (M+).

λ_(max) CH₂ Cl₂ (ε): 508 (60,000), 318 (3,400), 281 (6,800). Anal.Calc'd. for C₁₈ H₁₈ N₂ O₂ S: C, 66.2; H, 5.6; H, 8.6. Found: C, 66.1; H,5.6; N, 8.5.

(b) Preparation of Product (D-5)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylboron (0.737 g, 3.05mmol), in tetrahydrofuran (10 mL); and (2) ethyl6-(3-ethyl-2benzothiazolinylidene)-2-isocyano-2,4-hexadienoate (D-5a)(0.993 g, 3.05 mmol) in tetrahydrofuran (10 mL). The resulting magentaslurry was stirred 30 min at 0° C., then ethanol (40 mL) was added. Theproduct was isolated by filtration, washed with ethanol, and dried. Theresulting green solid (1.30 g 75%) was pure by NMR.

In a separate experiment, a portion was recrystallized fromdichloromethane/ethanol to give a green solid for analysis and meltingpoint (mp 147°-149° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.56 (1H, d, J=12.5), 7.46 (1H, d, J=7.7),7.39 -7.06 (19 H, m), 5.91 (1H, t, J=12.9), 5.57 (1H, d, J=12.2), 4.28(2H, q, J=7.1), 4.01 (2H, q, J=7.2), 1.41 (3H, t, J=7.2), 1.34 (3H, t,J=7.1). IR (KBr) 1700, 1565, 1485, 1465 cm⁻¹. FDMS (m/e) 568 (M+), 326.

λ_(max) CH₂ Cl₂ (ε): 555 (112,000), 525 (69,000 ) (sh), 276 (17,000).Anal. calc'd. for C₃₆ H₃₃ BN₂ O₂ S: C, 76.1; H, 5.9; N, 4.9. Found: C,75.8; H, 5.8; N, 5.2.

EXAMPLE 6 Preparation of Ethyl6-(3-ethyl-2-benzothiazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2,4-hexadioenoate(D-6)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)boron (1.03g, 3.48 mmol) in tetrahydrofuran (10 mL); and (2) ethyl6-(3-ethyl-2-benzothiazolinylidene)-2-isocyano-2,4-hexadienoate (D-5a)(1.13 g, 3.48 mmol) in tetrahydrofuran (10 mL). The resulting magentasolution was stirred 30 min at 0° C., then the solvent was removed underreduced pressure. The residue was triturated with ethanol, and theresulting magenta solid was isolated by filtration and dried (1.65 g,76%). The material was pure by NMR, and was used without furtherpurification.

In a separate experiment, a portion was recrystallized fromdichloromethane/ethanol to give a magenta solid (mp 146.5°-147° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.56 (1H, d, J=12.6), 7.48 (1H, d, J=7.8),7.38 (1H, t, J=7.7), 7.28 (6H, t, J=6.5), 7.22-7.10 (3H, m), 6.96 (6H,t, J=8.9), 5.70 (1H, br t, J=12.6), 5.52 (1H, d, J=12.2), 4.29 (2H, q,J=7.1), 4.04 (2H, q, J=7.1), 1.42 (3H, t, J=7.1), 1.34 (3H, t, J=7.1).IR (KBr) 1705, 1590, 1570, 1485, 1464 cm⁻¹. FDMS (m/e) 622 (M+), 326.

λ_(max) CH₂ Cl₂ (ε): 556 (118,000), 527 (66,000) (sh). Anal. calc'd. forC₃₆ H₃₀ BF₃ N₂ O₂ S: C, 69.5; H, 4.9; N, 4.5. Found: C, 69,2; H, 5.1; N,4.5.

EXAMPLE 7 Preparation of Ethyl4-(3-ethyl-2-benzoxazolinylidene)-2-triphenylborylisocyano-2-butenoate(D-8) (a) Preparation of Ethyl4-(3-ethyl-2-benzoxazolinylidene)-2-isocyano-2-butenoate (D-8a)

The same procedure was employed for the reaction and work-up as forExample 1 (D-1a), but using the following materials: (1) potassiumt-butoxide (2.8 g, 25 mmol); (2) ethyl isocyanoacetate (2.83 g, 25mmol); and (3) 2-(2-acetanilidovinyl)-3-ethylbenzoxazolium iodide (10.9g, 25 mmol). Trituration of the residue obtained after solventevaporation with 2:1 ethanol/ether gave 3.33 g (47%) D-8a as a powderyyellow solid that was homogeneous by TLC (3:7 ethylacetate/cyclohexane).

A portion of the material was recrystallized from ethanol to give yellowneedles that were used for analysis and melting point (135°-136.5° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.98 (1H, d, J=12.4), 7.29-7.20 (2H,overlapping d, t), 7.13 (1H, t, J=7.7), 7.00 (1H, d, J=7.6), 5.05 (1H,d, J=12.5), 4.27 (2H, q, J=7.1), 3.90 (2H, q, J=7.2), 1.40 (3H, t,J=7.2), 1.34 (3H, t, J=7.1). IR (KBr) 2125, 1685, 1640, 1610, 1570, 1480cm⁻¹. FDMS (m/e) 284 (M+).

λ_(max) CH₂ Cl₂ (ε): 408 (72,000). Anal. calc'd. for C₁₆ H₁₆ N₂ O₃ : C,67.6; H, 5.7; N, 9.9. Found: C, 67.6; H, 5.8; N, 9.8.

(b) Preparation of product (D-8)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (1.15 g, 4.75mmol) in tetrahydrofuran (15 mL); and (2) ethyl4-(3-ethyl-2-benzoxazolinylidene)-2-isocyano-2-butenoate (D-8a) (1.35 g,4.75 mmol) in tetrahydrofuran (15 mL). After the reaction had stirred 30min at 0° C., the solvent was removed under reduced pressure and theresidue was triturated with ethanol. The resulting yellow solid wasisolated by filtration and dried (crude yield 2.01 g, 80%).Recrystallization from dichloromethane/ethanol (hot filtration) gavepure D-8 (1.64 g, 66%) as a yellow flaky solid (mp 151°-151.5° C.).

¹ H NMR (300 MHz, CDCl₃) δ 8.19 (1H, d, J=13.0), 7.39-7.34 (7H; 6H, d,J=7.2; 1H, m), 7.31-7.23 (8H; 6H, t, J=7.2; 2H, m), 7.16 (3H, t, J=7.0),7.05 (1H, d, J=7.6), 4.86 (1H, d, J=13.0), 4.31 (2H, q, J=7.1), 3.55(2H, q, J=7.2), 1.38 (3H, t, J=7.1), 1.19 (3H, t, J=7.2), IR (KBr)2230(w), 1700, 1633, 1587, 1555, 1480 cm⁻¹. FDMS (m/e) 526 (M+) 284.

λ_(max) CH₂ Cl₂ (ε): 424 (87,000), 410 (63,000) (sh). Anal. calc'd. forC₃₄ H₃₁ BN₂ O₃ : C, 77.6; H, 5.9; N, 5.3. Found: C, 77.5; H, 5.9; N,5.3.

EXAMPLE 8 Preparation of Ethyl4-(3-ethyl-2-benzoxazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-9)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (0.919g, 3.10 mmol) in tetrahydrofuran (10 mL); and (2)ethyl-4-(3-ethyl-2-benzoxazolinylidene)-2-isocyano-2-butenoate (D-8a)(0.882 g, 3.10 mmol) in tetrahydrofuran (10 mL). After the reaction hadstirred 30 min at 0° C., the solvent was removed under reduced pressureand the residue was triturated with ethanol. The resulting yellow solidwas filtered and dried (crude yield: 1.35 g, 75%). Recrystallizationfrom dichloromethane/ethanol (hot filtration) gave pure D-9 (1.18 g,66%) as yellow plates (mp 156.5°-158° C.).

A second crop (0.13 g, 7%) that was pure by NMR was also isolated (totalyield: 1.31 g, 73%).

¹ H NMR (300 MHz, CDCl₃) δ 8.18 (1H, d, J=13.0), 7.36 (1H, d, J=8.0),7.33-7.21 (8H; 6H, dd, J=6.3, 8.1; 2H, m), 7.08 (1H, d, J=7.7), 6.94(6H, t, J=8.8), 4.73 (1H, d, J=13.0), 4.31 (2H, q, J=7.1), 3.59 (2H, q,J=7.2), 1.37 (3H, t, J=7.1), 1.21 (3H, t, J=7.2). IR (KBr) 2230(w),1700, 1635, 1587, 1560, 1495, 1480 cm⁻¹. FDMS (m/e) 580 (M+).

λ_(max) CH₂ Cl₂ (ε): 425 (91,000), 413 (70,000) (sh). Anal. calc'd. forC₃₄ H₂₈ BF₃ N₂ O₂ : C, 70.4; H, 4.9; N, 4.8. Found: C, 70.1; H, 4.8; N,4.7.

EXAMPLE 9 Preparation of Ethyl6-(3-ethyl-2-benzoxazolinylidene)-2-triphenylborylisocyano-2,4-hexadienoate(D-10) (a) Preparation of Ethyl6-(3-ethyl-2-benzoxazolinylidene-2-isocyano-2,4-hexadienoate (D-10a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide (5.6g, 50 mmol) in tetrahydrofuran (120 mL); (2) ethyl isocyanoacetate (5.65g, 50 mmol) in tetrahydrofuran (40 mL); (3)2-(4-acetanilido-1-butadienyl)-3-ethylbenzoxazolium iodide (23.0 g, 50mmol). Trituration of the residue obtained after solvent evaporationwith ethanol gave 2.02 g (13%) D-10a as a blue crystalline solid thatwas homogeneous by TLC (3:7 ethyl acetate/cyclohexane).

In a different experiment, a small portion of the crude material wasrecrystallized from ethanol for analysis and melting point(154.5°-155.5° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.45-7.37 (2H, overlapping d, t), 7.22-7.15(2H, overlapping d, t), 7.06 (1H, t, J=7.7), 6.91 (1H, t, J=7.7), 6.26(1H, dd, J=12.5, 13.6), 5.02 (1H, d, J=11.9), 4.26 (2H, q, J=7.1), 3.81(2H, q, J=7.2), 1.37 (3H, t, J=7.2), 1.33 (3H, t, J=7.1). IR (KBr) 2125,1685, 1640, 1610, 1570, 1480. FDMS (m/e) 310 (M+).

λ_(max) CH₂ Cl₂ (ε): 490 (71,000). Anal. calc'd. for C₁₈ H₁₈ N₂ O₃ : C,69.7; H, 5.8; N, 9.0. Found: C, 69.5; H, 5.6; N, 8.9.

(b) Preparation of Product (D-10)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylboron (0.919 g, 3.80mmol) in tetrahydrofuran (15 mL); and (2) ethyl6-(3-ethyl-2-benzoxazolinylidene)-2-isocyano-2,4-hexadienoate (D-10a)(1.18 g, 3.80 mmol) in tetrahydrofuran (10 mL). After the resulting redslurry had stirred 30 min at 0° C., the solvent was removed underreduced pressure and the residue was triturated with ethanol. Theresulting red solid was filtered and dried (crude yield: 1.67 g, 80%).Recrystallization from dichloromethane/ethanol (hot filtration) gavepure D-10 (1.29 g, 61%) as a red solid.

A second crop was obtained (0.18 g, 9% ) that was also pure by NMR(total yield: 1.47 g, 70%). A small portion was recrystallized fromacetonitrile to give tiny red needles (mp 145°-148° C., dec.).

¹ H NMR (300 MHz, CDCl₃) δ 7.60 (2H, m), 7.40 (6H, d, J=7.4), 7.27 (8H:6H, t, J=7.2; 2H, m), 7.18 (4H, m), 7.04 (1H, d, J=7.7), 5.91 (1H, t,J=12.1), 4.90 (1H, d, J=12.3), 4.29 (2H, q, J=7.1), 3.91 (2H, q, J=7.2),1.46 (3H, t, J=7.2), 1.35 (3H, t, J=7.1). IR (KBr) 2220(w), 1700, 1640,1620, 1570, 1565, 1500 cm⁻¹. FDMS (m/e) 552 (M+) 310.

λ_(max) CH₂ Cl₂ (ε): 520 (102,000), 499 (68,000) (sh). Anal. calc'd. forC₃₆ H₃₃ BN₂ O₃ : C, 78.3; H, 6.0; N, 5.1. Found: C, 78.1; H, 6.1; N,5.0.

EXAMPLE 10 Preparation of Ethyl6-(3-ethyl-2-benzoxazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2,4-hexadienoate(D-11)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)boron (1.16g, 3.92 mmol) in tetrahydrofuran (15 mL); and (2) ethyl6-(3-ethyl-2-benzoxazolinylidene)-2-isocyano-2,4-hexadienoate (D-10a)(1.21 g, 3.92 mmol) in tetrahydrofuran (10 mL). The reaction was stirred30 min at 0° C., then the solvent was removed under reduced pressure.The residue was triturated with ethanol, and the resulting red solid wasisolated by filtration and dried.

The crude material (1.75 g, slightly impure by NMR) was recrystallizedfrom dichloromethane/ethanol (hot filtration) to give pure D-11 (1.55 g,65%) as a red-brown crystalline solid (mp 167.5°-169° C., dec).

¹ H NMR (300 MHz, CDCl₃) δ 7.58 (2H, m), 7.41-7.13 (9H; 6H, dd, J=6.4,8.1; 3H, m), 7.07 (1H, d, J=7.8), 6.97 (6H, t, J=8.9), 5.64 (1H, t,J=12.1), 4.93 (1H, d, J=12.3), 4.30 (2H, q, J=7.1), 3.94 (2H, q, J=7.2),1.45 (3H, t, J=7.2), 1.35 (3H, t, J=7.1). IR (KBr) 2230(w), 1700, 1640,1620, 1585, 1570, 1495 cm⁻¹. FDMS (m/e) 606 (M+), 310.

λ_(max) CH₂ Cl₂ (ε): 521 (101,000), 497 (61,000) (sh). Anal. calc'd. forC₃₆ H₃₀ BF₃ N₂ O₃ : C, 71.3; H, 5.0; N, 4.6. Found: C, 70.9; H, 5.1; N,4.5.

EXAMPLE 11 Preparation of Ethyl4-(1-ethyl-2-quinolinylidene)-2-triphenylborylisocyano-2-butenoate(D-16) (a) Preparation of Ethyl4-(1-ethyl-2-quinolinylidene)-2-isocyano-2-butenoate (D-16a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide(3.36 g, 30 mmol) in tetrahydrofuran (90 mL); (2) ethyl isocyanoacetate(3.39 g, 30 mmol) in tetrahydrofuran (30 mL); (3)2-(2-acetanilidovinyl)-1-ethylquinolinium iodide (13.3 g, 30 mmol).Trituration of the residue obtained after solvent evaporation withethanol gave 5.18 g (59%) D-16a as an orange solid.

Recrystallization from ethanol (hot filtration) gave 4.42 g (50%) pureD-16a as an orange crystalline solid (mp 137.5°-139° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.93 (1H, d, J=12.7), 7.54 (1H, dt, J=1.1,8.0), 7.45 (1H, dd, J=1.0, 7.7), 7.39-7.28 (3H, m), 7.21 (1H, t, J=7.4),5.63 (1H, d, J=12.8), 4.31 (2H, q, J=7.1), 4.19 (2H, q, J=7.1), 1.50(3H, t, J=7.2), 1.38 (3H, t, J=7.1). IR (KBr) 2100, 1685, 1630, 1555cm⁻¹. FDMS (m/e) 294 (M+).

λ_(max) CH₂ Cl₂ (ε): 506 (25,000) (sh), 480 (42,000), 455 (39,000) (sh),387 (19,000). Anal. calc'd. for C₁₈ H₁₈ N₂ O₂ : C, 73.4; H, 6.2; N, 9.5.Found: C, 73.7; H, 6.3; N, 9.5.

(b) Preparation of Product (D-16)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (1.51 g, 6.24mmol) in tetrahydrofuran (20 mL); and (2) ethyl4-(1-ethyl-2-quinolinylidene-2-isocyano-2-butenoate (D-16a) (1.83 g,6.24 mmol) in tetrahydrofuran (20 mL). After the reaction slurry hadstirred 30 min at 0° C., ethanol (40 mL) was added and the precipitatedproduct was isolated by filtration, washed with ethanol, and dried togive an orange solid (2.79 g, 84%). It was pure by TLC and NMR, and wasused without further purification.

A portion was recrystallized from dichloromethane/ethanol (hotfiltration) to give an orange flaky solid (mp 174°-175° C.).

¹ H NMR (300 MHz, CDCl₃) δ 8.12 (1H, t, J=8.4), 7.60 (1H, t, J=8.4),7.55 (1H, d, J=7.8), 7.49 (2H, app s), 7.38 (7H: 6H, d, J=7.3; 1H,obscured), 7.34-7.24 (8H; 6H, t, J=6.9; 2H, obscured), 7.18 (3H, t,J=7.0), 5.53 (1H, d, J=13.3), 4.31 (2H, q, J=7.1), 3.82 (2H, br s), 1.41(3H, t, J=7.1), 1.02 (3H, t, J=7.1). IR (KBr) 2220, 1690, 1622, 1540,1490 cm⁻¹. FDMS (m/e) 536 (M+), 294, 242.

λ_(max) CH₂ Cl₂ (ε): 509 (47,000), 480 (57,000), 456 (39,000) (sh), 432(33,000) (sh). Anal. calc'd. for C₃₆ H₃₃ BN₂ O₂ : C, 80.6; H, 6.2; N,5.2. Found: C, 80.2; H, 6.2; N, 5.2.

EXAMPLE 12 Preparation of Ethyl4-(1-ethyl-2-quinolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-17)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (1.83g, 6.18 mmol) in tetrahydrofuran (20 mL); and (2) ethyl4-(1-ethyl-2-quinolinylidene)-2-isocyano-2-butenoate (D-16a) (1.82 g,6.18 mmol) in tetrahydrofuran (20 mL). After the reaction slurry hadstirred 30 min at 0° C., the solvent was removed under reduced pressure.The residue was triturated with ethanol and the resulting product wasisolated by filtration, washed with ethanol, and dried to give an orangesolid (3.01 g, 82%). It was pure by TLC and NMR, and was used withoutfurther purification.

A portion was recrystallized from dichloromethane/ethanol (hotfiltration) to give an orange flaky solid (mp 175°-176° C., dec).

¹ H NMR (300 MHz, CDCl₃) δ 8.13 (1H, d, J=13.4), 7.64 (1H, t, J=7.9),7.58 (1H, d, J=7.2), 7.52 (2H, m), 7.42 (1H, d, J=8.4), 7.35 (1H, t,J=7.5), 7.28 (6H, dd, J=6.4, 8.0), 6.96 (6H, d, J=8.8), 5.46 (1H, d,J=13.4), 4.32 (2H, q, J=7.1), 3.90 (2H, br s), 1.40 (3H, t, J=7.1), 1.07(3H, t, J=7.1). IR (KBr) 2220, 1695, 1623, 1587, 1540, 1495 cm⁻¹. FDMS(m/e) 590 (M+) 296, 294.

λ_(max) CH₂ Cl₂ (ε): 507 (48,000), 479 (55,000), 458 (34,000) (sh).Anal. calc'd. for C₃₆ H₃₀ BF₃ N₂ O₂ : C, 73.2; H, 5.4; N, 4.7. Found: C,73.2; H, 5.4; N, 4.7.

EXAMPLE 13 Ethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-triphenylborylisocyano-2-butenoate(D-19) (a) Preparation of Ethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-isocyano-2-butenoate(D-19a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide(1.93 g, 17.2 mmol) in tetrahydrofuran (60 mL); (2) ethylisocyanoacetate (1.94 g, 17.2 mmol) in tetrahydrofuran (20 mL); (3)2-(2-acetanilidovinyl)-5,6-dichloro-1,3-diethylbenzimidazolium iodide(9.11 g, 17.2 mmol). After the reaction had stirred overnight at ambienttemperature, the resulting slurry was poured into a 500 mL Erlenmeyer®flask with water (90 mL), saturated ammonium chloride (10 mL), and ethylacetate (100 mL). After stirring, the orange solid was filtered andwashed with water then ethyl acetate. It was then dried at ambienttemperature under vacuum to give 4.43 g (68%) D-19a that wascontaminated with a trace amount of the benzimidazolium startingmaterial by TLC (3:7 ethyl acetate/cyclohexane) and NMR. Due todifficulties encountered previously in purification of the material, itwas used without purification.

In a different experiment, a small portion of the crude material wasrecrystallized from acetonitrile for full characterization (mp 245°-250°C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.82 (1H, d, J=13.8), 7.17 (2H, s), 5.05 (1H,d, J=13.8), 4.22 (2H, q, J=7.1), 4.07 (4H, q, J=7.2), 1.48 (6H, t,J=7.2), 1.33 (3H, t, J=7.1). IR (KBr): 2100, 1685, 1570, 1500 cm⁻¹. FDMS(m/e) 379 (M+).

λ_(max) CH₂ Cl₂ (ε): 440 (112,000), 422 (61,000) (sh). Anal. calc'd. forC₁₈ H₁₉ Cl₂ N₃ O₂ : C, 56.9; H, 5.0; N, 11.1. Found: C, 56.5; H, 5.1; N,10.8.

(b) Preparation of D-19

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (1.23 g, 5.09mmol) in tetrahydrofuran (15 mL); and (2) ethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-isocyano-2-butenoate(D-19a) (1.93 g, 5.09 mmol) in tetrahydrofuran (15 mL). After thereaction slurry had stirred 30 min at 0° C., the solvent was removedunder reduced pressure. The residue was triturated with ethanol and theresulting product was isolated by filtration, washed with ethanol, anddried to give a yellow solid (2.46 g). By NMR, the crude product wascontaminated with unreacted D-19a, probably due to poor qualitytriphenylborane. The crude product was slurried in tetrahydrofuran (30mL), and the slurry was cooled to 0° C. Additional triphenylborane(0.285 g, 1.18 mmol) (weighed out in a glove bag as before) intetrahydrofuran (5 mL) was added, and the reaction run and worked up asabove to give the crude product (2.62 g) as a yellow solid,uncontaminated by unreacted starting material.

Recrystallization from dichloromethane/ethanol (without heating, roomtemperature filtration) gave, in two crops, pure D-19 (total yield: 2.12g, 67%) as a yellow flaky solid (mp 178°-180° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.90 (1H, d, J=14.4), 7.36 (6H, d, J=7.1),7.26-7.12 (11H, m), 4.94 (1H, d, J=14.5), 4.27 (2H, q, J=7.1), 3.84 (4H,q, J=7.1), 1.38 (3H, t, J=7.1), 1.31 (6H, t, J=7.1). IR (KBr) 1705,1695, 1555, 1490, 1450 cm⁻¹. FDMS (m/e) 621 (M+) 379.

λ_(max) CH₂ Cl₂ (ε): 446 (116,000), 429 (64,000) (sh). Anal. calc'd. forC₃₆ H₃₄ BCl₂ N₃ O₂ : C, 69.5; H, 5.5; N, 6.8. Found: C, 69.6; H, 5.6; N,6.9.

EXAMPLE 14 Ethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-20)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (1.12g, 3.80 mmol) in tetrahydrofuran (15 mL); and (2) ethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-isocyano-2-butenoate(D-19a) (1.44 g, 3.80 mmol) in tetrahydrofuran (15 mL). After thereaction slurry had stirred 30 min at 0° C., the solvent was removedunder reduced pressure. The residue was triturated with ethanol and theresulting product was isolated by filtration, washed with ethanol, anddried to give a yellow solid (2.25 g).

Recrystallization from dichloromethane/ethanol (without heating, roomtemperature filtration) gave, in two crops, pure D-20 (total yield: 1.97g, 77%) as a yellow crystalline solid (mp 144°-148° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.89 (1H, d, J=14.4), 7.28-7.23 (8H, m), 6.93(6H, t, J=9.0), 4.85 (1H, d, J=14.5), 4.27 (2H, q, J=7.1), 3.89 (4H, q,J=7.2), 1.36 (3H, t, J=7.2), 1.33 (6H, t, J=7.2). IR (KBr) 1695, 1595,1560, 1510, 1450 cm⁻¹. FDMS (m/e) 675 (M+) 379.

λ_(max) CH₂ Cl₂ (ε): 445 (102,000), 426 (54,000) (sh). Anal. calc'd. forC₃₆ H₃₁ BCl₂ F₃ N₃ O₂ : C, 63.9; H, 4.6; N, 6.2; Cl, 10.3. Found: C,63.8; H, 4.6; N, 6.1; Cl, 10.3.

EXAMPLE 15 Ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene)-2-triphenylborylisocyanoacetate(D-22) (a) Preparation of Ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene-2-isocyanoacetate(D-22a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide (5.6g, 50 mmol) in tetrahydrofuran (120 mL); (2) ethyl isocyanoacetate (5.65g, 50 mmol) in tetrahydrofuran (40 mL); (3)4,5-dihydronaphtho-2-(2-thiopropyl)[1,2-d]-1,3-dithioliumhexafluorophosphate (21.2 g, 50 mmol). After the reaction was stirredovernight at ambient temperature, water (90 mL), saturated ammoniumchloride (10 mL), and ethyl acetate (150 mL) were added. The undissolvedmaterial was filtered, then slurried in 1:1 ethanol/ether, filteredagain and dried to give (1) (3.5 g). The original filtrate wastransferred to a separatory funnel and extracted three times with ethylacetate. The combined extracts were washed with saturated sodiumchloride, dried over sodium sulfate, and filtered, and the solvent wasremoved under reduced pressure. The residue was triturated with 1:1ethanol/water, and the tan solid was filtered to give (2) (2.7 g). ByNMR, (1) and (2) appeared to be double bond isomers of the desiredproduct, each contaminated by a small amount of the other. (1) wasrecrystallized from dichloromethane/ethanol to give pure materialD-22a(1) (2.25 g) (2) was flash chromatographed with 15:85 ethylacetate/cyclohexane to give after trituration with 1:1 ethanol/etherpure D-22a(2) (0.28 g). A second group of fractions gave afterevaporation and trituration as above 0.96 g D-22a(2) contaminated with asmall amount of D-22a(1). The remaining fractions contained mixtures andwere combined with the mother and wash liquors from the crystallizationof D-22a(1) and the trituration of chromatographed material, and thesolvent was removed under reduced pressure to give a tan solid (1.06 g)that was a mixture of D-22a(1) and D-22a(2) by NMR and TLC (20:80 ethylacetate/cyclohexane). The total yield was 4.55 g (29%). D-22a(1) andD-22a(2) were fully characterized separately, although the double bondgeometries could not be assigned.

D-22a(1) mp 184.5°-188° C., dec. (dichloromethane/ethanol).

¹ H NMR (300 MHz, CDCl₃) δ 7.30-7.25 (3H, m), 7.17 (1H, m), 4.34 (2H, q,J=7.1), 3.07 (2H, t, J=7.9), 2.79 (2H, t, J=7.9), 1.39 (3H, t, J=7.1).IR (KBr): 2085, 1680, cm⁻¹. FDMS (m/e) 315 (M+).

λ_(max) CH₂ Cl₂ (ε): 391 (25,000) 377, (21,000). Anal. calc'd. for C₁₆H₁₃ NO₂ S₂ : C, 60.9; H, 4.2; N, 4.4. Found: C, 60.8; H, 4.3; N, 4.4.

D-22a(2) mp 175°-177° C., dec. (dichloromethane/ethanol).

¹ H NMR (300 MHz, CDCl₃) δ 7.27 (4H, m), 4.36 (2H, q, J=7.1), 3.08 (2H,t, J=7.9), 2.81 (2H, t, J=7.9), 1.41 (3H, t, J=7.1). IR (KBr): 2100,1670 cm⁻¹. FDMS (m/e) 315 (M+).

λ_(max) CH₂ Cl₂ (ε): 390 (25,000), 377 (21,000). Anal. calc'd. for C₁₆H₁₃ NO₂ S₂ : C, 60.9; H, 4.2; N, 4.4. Found: C, 60.6; H, 4.2; N, 4.3.

(b) Preparation of D-22

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (0.330 g, 1.36mmol) in tetrahydrofuran (5 mL); and (2) ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene-2-isocyanoacetate(D-22a) (0.430 g, 1.36 mmol, mixture of olefin isomers) intetrahydrofuran (5 mL). After the reaction slurry had stirred 30 min at0° C., the solvent was removed under reduced pressure. The residue wasdissolved in warm dichloromethane, filtered, and precipitated withethanol to give pure D-15 (mixture of olefin isomers) (0.636 g, 84%) asa yellow solid (mp 119°-121° C., dec).

A small portion was recrystallized a second time for analysis.

¹ H NMR (300 MHz, CDCl₃) δ 7.45-7.19 (19H, m), 4.38 (2H, q, J=7.1), 3.09(2H, t, J=7.9), 2.82 (2H, t, J=7.9), 1.41 (3H, q, J=7.1). IR (KBr) 2210,1680, 1460, 1445, 1430 cm⁻¹. FDMS (m/e) 557 (M+) 315.

λ_(max) CH₂ Cl₂ (ε): 406 (26,000). Anal. calc'd. for C₃₄ H₂₈ BNO₂ S₂ :C, 73.2; H, 5.1; N, 2.5. Found: C, 73.1; H, 5.3; N, 2.5.

EXAMPLE 16 Ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene)-2-tri(p-fluorophenyl)borylisocyanoacetate(D-23)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (1.14g, 3.85 mmol) in tetrahydrofuran (10 mL); and (2) ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene)-2-isocyanoacetate(D-22a) (1.21 g, 3.85 mmol, mixture of olefin isomers) intetrahydrofuran (10 mL). After the reaction slurry had stirred 30 min at0° C., the solvent was removed under reduced pressure. The residue wastriturated with ethanol to give D-23 (1.90 g, mixture of double bondisomers) as a yellow solid. The material was pure by NMR with theexception of a small amount of residual tetrahydrofuran.

A portion (0.885 g) was recrystallized from dichloromethane/ethanol (hotfiltration) to give pure material (0.734 g) for analysis and yield (81%crude X 83% recovery=67% total yield). The pure material (a mixture ofolefin isomers) was obtained as a yellow-orange solid (mp 117°-127° C.,dec).

¹ H NMR (300 MHz, CDCl₃) δ 7.31-7.22 (10H, m), 6.95 (6H, t, J=8.8), 4.34(2H, q, J=7.1), 3.09-3.02 (2H, m), 2.84-2.78 (2H, m), 1.36 (3H, t,J=7.1). IR (KBr) 2220, 1685, 1585, 1470, 1445 cm⁻¹. FDMS (m/e) 611 (M+),315, 296.

λ_(max) CH₂ Cl₂ (ε): 406 (28,000). Anal. calc'd. for C₃₄ H₂₅ BF₃ NO₂ S₂: C, 66.8; H, 4.1; N, 2.3. Found: C, 66.8; H, 4.2; N, 2.3.

EXAMPLE 17 Preparation of Ethyl4-(4,6-diphenyl-2-pyranylidene)-2-triphenylborylisocyano-2-butenoate(D-24) (a) Preparation of Ethyl4-(4,6-diphenyl-2-pyranylidene)-2-isocyano-2-butenoate (D-24a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide (2.8g, 25 mmol) in tetrahydrofuran (100 mL); (2) ethyl isocyanoacetate (2.82g, 25 mmol) in tetrahydrofuran (20 mL); (3)2-(2-dimethylaminovinyl)-4,6-diphenylpyrilium perchlorate (10 g, 25mmol). Ethanol trituration of the residue obtained after solventevaporation gave 3.58 g D-24a as a black crystalline solid. The crudematerial was recrystallized from ethanol with a hot filtration to give2.12 g D-24a(1) as a black crystalline solid. The material that hadcrystallized in the filter funnel during the hot filtration wasrecrystallized from dichloromethane/ethanol to give 0.44 g D-24a(2). Themother and wash liquors from D-24a(1) and D-24a(2) were combined and thesolvent was removed under reduced pressure. The residue wasrecrystallized from dichloromethane/ethanol to give 0.30 g D-24a(3) (mp150.5°-152° C.). All three crops (total: 2.92 g, 32%) were homogeneousand identical by TLC (dichloromethane), but by NMR they were mixtures ofdouble bond isomers in various proportions (D-24a(1): 4:1 isomer ratio;D-24a(2): 1:1 isomer ratio; D-24a(3): >9:1 isomer ratio). This wasirrelevant for subsequent chemistry, so no attempt was made to separatethem.

For simplicity, the NMR data for D-24a(3) is given. The other analyticaldata was essentially the same for all three crops.

¹ H NMR (300 MHz, CDCl₃) δ 8.06 (1H, d, J=12.5), 7.86-7.83 (2H, m),7.65-7.62 (2H, m), 7.54-7.52 (6H, m), 6.76 (1H, d, J=1.1), 6.70 1H, d,J=1.0), 5.76 (1H, d, J=12.5), 4.35 (2H, q, J=7.1), 1.42 (3H, t, J=7.1).IR (KBr): 2110, 1700, 1635, 1585, 1575, 1545, 1510, 1490 cm⁻¹. FDMS(m/e) 369 (M+).

λ_(max) CH₂ Cl₂ (ε): 536 (17,400), 504 (17,400), 407 (15,800), 388(17,100), 309 (23,000). Anal. calc'd. for C₂₄ H₁₉ NO₃ : C, 78.0; H, 5.2;N, 3.8. Found: C, 78.2; H, 5.3; N, 3.7.

(b) Preparation of Product (D-24)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (0.607 g, 2.51mmol) in tetrahydrofuran (5 mL); and (2) ethyl4-(4,6-diphenyl-2-pyranylidene)-2-isocyano-2-butenoate (D-24a) (0.923 g,2.51 mmol) in tetrahydrofuran (5 mL). After the reaction slurry hadstirred 30 min at 0° C., the solvent was removed under reduced pressure.The residue was triturated with ether and filtered, giving a black solid(1.31 g). The crude product was dissolved in warm dichloromethane,filtered, and precipitated with ethanol to give pure D-24 (1.13 g, 73%,mixture of double bond isomers) as a black crystalline solid.

A small portion was purified by chromatography on silica gel (elutingwith 20/80 dichloromethane/cyclohexane), then a secondrecrystallization, giving material for analysis (mp 148.5°-150° C.).

¹ H NMR (300 MHz, CDCl₃) δ 8.20 (1H, d, J=13.0), 7.83 (2H, m), 7.64 (2H,m), 7.58-7.53 (6H, m), 7.42 (6H, d, J=6.9), 7.30 (6H, t, J=6.9), 7.21(3H, t, J=7.2), 6.88 (1H, d, J=0.9), 6.47 (1H, s), 5.34 (1H, d, J=12.8),4.36 (2H, q, J=7.1), 1.41 (3H, t, J=7.1), as well as small peaks fromthe minor olefin isomer. IR (KBr) 2220, 1710, 1633, 1585, 1573, 1543,1507, 1485 cm⁻¹. FDMS (m/e) 611 (M+), 369.

λ_(max) CH₂ Cl₂ (ε): 636 (8,400) (sh), 580 (20,000) (sh), 544 (24,300),513 (20,900) (sh), 409 (13,900), 391 (13,100), 317 (20,300). Anal.calc'd. for C₄₂ H₃₄ BNO₃ : C, 82.5; H, 5.6; N, 2.3. Found: C, 82.7; H,5.8; N, 2.4.

EXAMPLE 18 Preparation of Ethyl4-(4,6-diphenyl-2-pyranylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-25)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (0.845g, 2.85 mmol) in tetrahydrofuran (5 mL); and (2) ethyl4-(4,6-diphenyl-2-pyranylidene)-2-isocyano-2-butenoate (D-24a) (1.05 g,2.85 mmol) in tetrahydrofuran (5 mL). After the reaction slurry hadstirred 30 min at 0° C., the solvent was removed under reduced pressure.The residue was triturated with ether and filtered, giving a black solid(1.13 g). The crude product was dissolved in warm dichloromethane,filtered, and precipitated with ethanol to give D-25 (0.780 g, mixtureof double bond isomers) as an oily black crystalline solid. A secondrecrystallization gave pure D-25 as a black crystalline solid (0.560 g,56%).

A small portion was purified by chromatography on silica gel (elutingwith 20/80 dichloromethane/cyclohexane), then another recrystallization,giving material for analysis (mp 139°-141° C., dec).

¹ H NMR (300 MHz, CDCl₃) δ 8.24 (1H, d, J=13.0), 7.88-7.84 (2H, m),7.71-7.66 (2H, m), 7.60-7.56 (6H, m), 7.35-7.30 (6H, dd, J=6.3, 8.1),7.05-6.99 (6H, t, J=8.8), 6.95 (1H, d, J=1.0), 5.28 (1H, d, J=13.0),4.38 (2H, q, J=7.1), 1.42 (3H, t, J=7.1). IR (KBr) 1710, 1635, 1585,1540, 1485 cm⁻¹. FDMS (m/e) 665 (M+), 369, 296.

λ_(max) CH₂ Cl₂ (ε): 629 (9,400) (sh), 574 (21,000) (sh), 544 (25,100),513 (21,500) (sh), 409 (14,100), 391 (13,100), 317 (20,700). Anal.calc'd. for C₄₂ H₃₁ BF₃ NO₃ : C, 75.8; H, 4.7; N, 2.1, Found: C, 75.4;H, 4.9; N, 2.0.

EXAMPLE 19 Preparation of Ethyl4-(2,6-diphenyl-4-pyranylidene)-2-triphenylborylisocyano-2-butenoate(D-29) (a) Preparation of Ethyl4-(2,6-diphenyl-4-pyranylidene)-2-isocyano-2-butenoate (D-29a)

The same procedure was employed for the reaction as for Example 1(D-1a), but using the following materials: (1) potassium t-butoxide(1.68 g, 15 mmol) in tetrahydrofuran (50 mL); (2) ethyl isocyanoacetate(1.69 g, 15 mmol) in tetrahydrofuran (15 mL); (3)2-(2-dimethylaminovinyl)-4,6-diphenylpyrilium perchlorate (6.02 g, 15mmol). After the reaction was stirred overnight at ambient temperature,it was poured onto water (75 mL) and saturated ammonium chloride (25mL), and extracted twice with ethyl acetate (75 mL). There was a largeamount of undissolved orange solid, and it was removed from both theaqueous and organic layers by filtration. (It was usbsequently found tobe unreacted starting material.) The aqueous layer was extracted oncemore with ethyl acetate, and the work-up completed as in Example 1(D-1a). Ethanol trituration of the residue obtained after solventevaporation gave 1.51 g (27%) D-29a as a flaky orange solid that washomogeneous by TLC (3:7 ethyl acetate/cyclohexane).

A small portion of the crude material was recrystallized from ethanolfor analysis and melting point (mp 145°-145.5° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.87-7.80 (4H, m) 7.84 (1H, d, J=12.6),7.54-7.50 (6H, m), 6.99 (1H, s), 6.70 (1H, s), 6.00 (1H, d, J=12.9),4.35 (2H, q, J=7.1), 1.40 (3H, t, J=7.1). IR (KBr): 2125, 1710, 1653,1553, 1493 cm⁻¹. FDMS (m/e) 369 (M+).

λ_(max) CH₂ Cl₂ (ε): 470 (36,800) (sh), 446 (40,600), 314 (13,800).Anal. calc'd. for C₂₄ H₁₉ NO₃ : C, 78.0; H, 5.2; N, 3.8. Found: C, 78.1,H, 5.3; N, 3.7.

(b) Preparation of Product (D-29)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (0.361 g, 1.49mmol) in tetrahydrofuran (5 mL); and (2) ethyl4-(2,6-diphenyl-4-pyranylidene)-2-isocyano-2-butenoate (D-29a) (0.550 g,1.49 mmol) in tetrahydrofuran (5 mL). After the orange reaction slurryhad stirred 30 min at 0° C., the solvent was removed under reducedpressure. The residue was triturated with ether and filtered, giving anorange solid (0.804 g). The crude product was dissolved in warmdichloromethane, filtered, and precipitated with ethanol to give pureD-29 (0.654 g, 73%) as a red-orange flaky solid (mp 117°-120° C., dec).

A second crop (0.060 g 7%) was also obtained (total yield 0.714 g, 80%).

¹ H NMR (300 MHz, CDCl₃) δ 8.07 (1H, d, J=13.3), 7.92-7.85 (4H, m),7.60-7.57 (6H, m), 7.46-7.43 (6H, m), 7.33 (6H, t, J=7.2), 7.25 (3H, t,J=7.1), 7.12 (1H, s), 6.48 (1H, d, J=0.9), 5.65 (1H, d, J=13.3), 4.39(2H, q, J=7.1), 1.43 (3H, t, J=7.1). IR (KBr) 2225, 1710, 1650, 1565,1545, 1493 cm⁻¹. FDMS (m/e) 611 (M+), 369.

λ_(max) CH₂ Cl₂ (ε): 519 (18,800), 492 (29,500), 470 (25,700), 330(8,000). Anal. calc'd. for C₄₂ H₃₄ BNO₃ : C, 82.5; H, 5.6; N, 2.3. FoundC, 80.7; H, 5.9; N, 2.2.

EXAMPLE 20 Preparation of Ethyl4-(2,6-diphenyl-4-pyranylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-30)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (0.475g, 1.60 mmol) in tetrahydrofuran (5 mL); and (2) ethyl4-(2,6-diphenyl-4-pyranylidene)-2-isocyano-2-butenoate (D-29a) (0.592 g,1.60 mmol) in tetrahydrofuran (5 mL). After the orange reaction slurryhad stirred 30 min at 0° C., the solvent was removed under reducedpressure. The residue was triturated with ether and filtered, giving anorange solid (0.854 g). The crude product was dissolved in warmdichloromethane, filtered and precipitated with ethanol to give pureD-30 (0.709 g, 67%) as a red-orange flaky solid (mp 114°-120° C., dec).

A second crop (0.016 g, 2%) was also obtained (total yield 0.725 g,69%).

¹ H NMR (300 MHz, CDCl₃) δ 8.08 (1H, d, J=13.3), 7.93-7.86 (4H, m),7.64-7.59 (6H, m), 7.32 (6H, dd, J=6.5, 8.3), 7.14 (1H, s), 7.03 (6H, t,J=8.8), 6.49 (1H, s), 5.57 (1H, d, J=13.3), 4.39 (2H, q, J=7.1), 1.42(3H, t, J=7.1). IR (KBr) 2225, 1710, 1650, 1585, 1567, 1545, 1493 cm⁻¹.FDMS (m/e) 665 (M+), 369.

λ_(max) CH₂ Cl₂ (ε): 525 (32,200), 493 (48,700), 470 (41,700) (sh), 330(12,800). Anal. calc'd. for C₄₂ H₃₁ BF₃ NO₃ : C, 75.8; H, 4.7; N, 2.1.Found: C, 75.4; H, 5.2; N, 2.2.

EXAMPLE 21 Preparation of Ethyl4-(1-ethyl-4-quinolinylidene)-2-triphenylborylisocyano-2-butenoate(D-31) (a) Preparation of Ethyl4-(1-ethyl-4-quinolinylidene)-2-isocyano-2-butenoate (D-31a)

The same procedure was employed for the reaction as for Example 1 (D-1a)but using the following materials: (1) potassium t-butoxide (5.80 g,51.8 mmol) in tetrahydrofuran (140 mL); (2) ethyl isocyanoacetate (5.86g, 51.8 mmol) in tetrahydrofuran (60 mL); (3)4-(2-acetanilidovinyl)-1-ethylquinolinium iodide (23.0 g, 51.8 mmol).After the reaction was stirred overnight at ambient temperature, it waspoured onto water (300 mL) and saturated ammonium chloride (100 mL).Attempts to extract with ethyl acetate led to crystallization of theproduct, so the ethyl acetate/product suspension was evaporated underreduced pressure. The residue was dissolved in dichloromethane, andcombined with dichloromethane extractions of the aqueous layer. Thework-up was completed as in Example 1 (D-1a).

After filtration, the dichloromethane was concentrated to 100-150 mL,and then warmed to take the material into solution. Ethanol (150-200 mL)was added. Crystals formed upon cooling in the refrigerator, and thesewere collected by filtration to give 11.1 g (73%) D-31a as black flakycrystals (mp 161.5°-162.5° C.).

¹ H NMR (300 MHz, CDCl₃) δ 8.17 (1H, d, J=8.2), 7.96 (1H, d, J=12.8),7.57 (1H, t, J=7.7), 7.31 (2H, m), 7.01 (1H, d, J=5.6), 6.67 (1H, d,J=7.7), 6.46 (1H, d, J=12.9), 4.32 (2H, q, J=7.1), 4.06 (2H, q, J=7.2),1.48 (3H, t, J=7.2), 1.39 (3H, t, J=7.1). IR (KBr) 2100, 1670, 1630,1535 cm⁻¹. FDMS (m/e) 294 (M+).

λ_(max) CH₂ Cl₂ (ε): 544 (35,000), 510 (39,000), 483 (24,000). Anal.calc'd. for C₁₈ H₁₈ N₂ O₂ : C, 73.4; H, 6.2; N, 9.5. Found: C, 73.0; H,6.1; N, 9.4.

(b) Preparation of Product (D-31)

The same procedure was employed for the reaction as for Example 1 (D-1)but using the following materials: (1) triphenylborane (3.39 g, 14.0mmol) in tetrahydrofuran (40 mL); and (2) ethyl4-(1-ethyl-4-quinolinylidene)-2-isocyano-2-butenoate (D-31a) (4.12 g,14.0 mmol) in tetrahydrofuran (125 mL). After the reaction slurry hadstirred 30 min, warming from 0° C. to ambient temperature, ethanol (150mL) was added and the precipitated product was isolated by filtration,washed with ethanol, and dried. A second crop was obtained by removingsome of the solvent under reduced pressure (total crude yield, 6.31 g).The red-gold solid was dissolved in warm dichloromethane (250 mL),filtered, and ethanol (200 mL) was added to induce crystallization. Theprecipitate was collected by filtration, washed with ethanol, and dried(4.03 g) to give small red-gold crystals (mp 168°-168.5° C.).

A second crop have additional red-gold solid (1.99 g), for a total yieldof 6.02 g, 80%).

¹ H NMR (300 MHz, CDCl₃) δ 8.12 (1H, d, J=13.4), 7.64 (1H, t, J=7.9),7.52-7.18 (19H, m), 6.87 (1H, d, J=7.6), 6.24 (1H, d, J=13.5), 4.32 (2H,q, J=7.1), 4.16 (2H, q, J=7.1), 1.50 (3H, t, J=7.2), 1.40 (3H, t,J=7.1). IR (KBr) 1690, 1620, 1530 cm⁻¹. FDMS (m/e) 536 (M+), 294.

λ_(max) CH₂ Cl₂ (ε): 555 (85,000), 519 (53,000, 489 (20,000) (sh). Anal.calc'd. for C₃₆ H₃₃ BN₂ O₂ : C, 80.6; H, 6.2; N, 5.2. Found: C, 80.5; H,6.1; N, 5.1.

EXAMPLE 22 Preparation of Ethyl4-(1-ethyl-4-quinolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate(D-32)

The same procedure was employed for the reaction as for Example 1 (D-1)but using the following materials: (1) tris(p-fluorphenyl)borane (4.00g, 13.5 mmol) in tetrahydrofuran (40 mL); and (2) ethyl4-(1-ethyl-4-quinolinylidene)-2-isocyano-2-butenoate (D-31a) (3.98 g,13.5 mmol) in tetrahydrofuran (125 mL). The reaction was stirred 30 min,warming from 0° C. to ambient temperature. The solvent was removed underreduced pressure, and the residue was triturated with ethanol (75 mL).After warming slightly then recooling, the resulting product wasisolated by filtration, washed with ethanol, and dried to give a darkgreen solid (7.11 g). Recrystallization from dichloromethane/ethanol(hot filtration) gave pure D-32 (6.25 g, 78%) as small dark greenneedles (mp 164.5°-166° C.).

¹ H NMR (300 MHz, CDCl₃) δ 8.10 (1H, d, J=13.5), 7.66 (1H, t, J=7.8),7.41 (2H, m), 7.36-7.26 (8H, m), 6.96 (6H, t, J=8.8), 6.89 (1H, d,J=4.6), ;b 6.12 (1H, d, J=13.4), 4.30 (2H, q, J=7.1), 4.17 (2H, q,J=7.1), 1.50 (3H, t, J=7.2), 1.36 (3H, t, J=7.1). IR (KBr) 1690, 1620,1585, 1530, 1495 cm⁻¹. FDMS (m/e) 590 (M+), 294.

λ_(max) CH₂ Cl₂ (ε): 555 (90,000), 519 (54,000). Anal. calc'd. for C₃₆H₃₀ BF₃ N₂ O₂ : C, 73.2; H, 5.1; N, 4.7. Found: C, 73.3; H. 5.4; N, 4.4.

EXAMPLE 23 Preparation of Ethyl3-dimethylamino-2-triphenylborylisocyano-2-propenoate (D-33)

The same procedure was employed for the reaction as for Example 1 (D-1)but using the following materials: (1) triphenylborane (1.99 g, 8.22mmol) in tetrahydrofuran (10 mL); and (2)3-dimethylamino-2-isocyano-2-propenoate (1.38 g, 8.22 mmol, prepared asdescribed in U. Schollkopf, P.-H. Porsch, H.-H. Lau, Justus Liebigs Ann.Chem., 1444 (1979) in tetrahydrofuran (10 mL). The reaction was allowedto warm to ambient temperature and stir overnight, then the solvent wasevaporated under reduced pressure. The resulting oily solid wastriturated with ether, and the product was isolated by filtration as alight yellow solid (1.87 g, 55%).

In another experiment, recrystallization from methylenechloride/cyclohexane (hot filtration) gave analytically pure material asa white crystalline solid (mp 114°-116.5° C.).

¹ H NMR (270 MHz, CDCl₃) δ 7.35 (1H, s), 7.28 (6H, dd, J=1.5, 8),7.22-7.05 (9H, m) 4.23 (2H, q, J=7), 3.09 (3H, br s), 2.78 (3H, br s),1.32 (3H, q, J=7). IR (KBr) 2225, 1720, 1650 cm⁻¹. FDMS (m/e) 410 (M+),242.

λ_(max) CH₂ Cl₂ (ε): 294 (20,400). Anal. calc'd. for C₂₆ H₂₇ BN₂ O₂ : C,76.1; H, 6.6; N, 6.8; B, 2.6. Found: C, 76.3; H, 6.6; N, 6.8; B, 2.7.

EXAMPLE 24 Preparation of Ethyl3-dimethylamino-2-tri(p-fluorophenyl)borylisocyano-2-propenoate (D-34)

The same procedure was employed for the reaction as for Example 1 (D-1)but using the following materials: (1) tris(p-fluorophenyl)borane (0.913g, 3.1 mmol) in tetrahydrofuran (10 mL); and (2)3-dimethylamino-2-isocyano-2-propenoate (see Example 23) (0.518 g, 3.08mmol) in tetrahydrofuran (5 mL). The reaction was stirred 1 hour at 0°C. and 1 hour at ambient temperature, then the solvent was evaporatedunder reduced pressure. Trituration with ether gave D-34 (0.76 g, 53%)as a white crystalline solid.

A small portion was recrystallized from methylene chloride/ether foranalysis (mp 124.5°-127.5° C.).

¹ H NMR (270 MHz, CDCl₃) δ 7.40 (1H, s), 7.18 6H, dd, J=6, 8.5), 6.92(6H, m), 4.28 (2H, q, J=7), 3.18 (3H, br s), 2.88 (3H, br s), 1.36 (3H,t, J=7). IR (KBr) 2225, 1705, 1640 cm⁻¹. FDMS (m/e) 464 (M+), 296.λ_(max) CH₂ Cl₂ (ε): 293 (19,500).

Anal. calc'd. for C₂₆ H₂₄ BF₃ N₂ O₂ : C, 67.3; H, 5.2; N, 6.0; B, 2.3.Found: C, 67.2; H, 5.3; N, 6.0; B, 2.0.

EXAMPLE 25 Preparation of Ethyl3,3-bis(dimethylamino)-2-triphenylborylisocyano-2-propenoate (D-36) (a)Preparation of Ethyl 3,3-bis(dimethylamino)-2-isocyano-2-propenoate(D-36a)

To a slurry of potassium t-butoxide (4.48 g, 40 mmol) in dry, distilledtetrahydrofuran (40 mL) in a 3-neck 250 mL flask at -78° C., under argonwas added dropwise from an addition funnel a solution of ethylisocyanoacetate (4.52 g, 40 mmol) in dry, distilled tetrahydrofuran (40mL). The anion was allowed to form for 25 min at -78° C., then solidbis(dimethylamino)ethoxymethylium tetrafluoroborate [9.28 g, 40 mmol,prepared as described by von H. Meerwein, W. Florian, N. Schon, G.Stopp, Justus Liebigs Ann. Chem. 641, 1, (1960)] was added as quickly aspossible through a powder funnel with a stream of argon. The reactionwas allowed to warm to ambient temperature and stir for 4 hours. It wasthen poured onto water (200 mL) and saturated ammonium chloride (40 mL)and extracted three times with ethyl acetate (100 mL). The combinedextracts were washed with water and saturated sodium chloride, driedover sodium sulfate, and the solvent removed under reduced pressure. Theresulting brown oil (6.9 g) was flash chromatographed, eluting withethyl acetate, to give slightly impure D-36a as a brown oil (4.78 g,57%). It was used without further purification

¹ H NMR (90 MHz, CDCl₃) δ 4.16 (2H, q, J=7), 2.87 (12H, s), 1.32 (3H, t,J=7).

(b) Preparation of Product (D-36)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (1.94 g, 8.02mmol) in tetrahydrofuran (8 mL); and (2)3,3-bis(dimethylamino)-2-isocyano-2-propenoate (D-36a) (1.69 g, 8.02mmol) in tetrahydrofuran (8 mL). After the reaction had stirred 1.5 hourat 0° C., the solvent as evaporated under reduced pressure.

The residue was recrystallized from ethanol (hot filtration) to givepure D-36 (2.63 g, 72%) as an off-white crystalline solid (mp141.5°-143° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.35 (6H, d, J=6.8), 7.25 (6H, t, J=7.1),7.17 (3H, d, J=7.1), 4.23 (2H, q, J=7.1), 2.92 (6H, br s), 2.72 (3H, brs), 2.65 (3H, br s), 1.35 (3H, t, J=7.1). IR (IBr) 1700, 1570, 1540cm⁻¹. FDMS (m/e) 453 (M+), 242, 211. λ_(max) CH₂ Cl₂ (ε): 296 (19,200).

Anal. calc'd. for C₂₈ H₃₂ BN₃ O₂ : C, 74.2; H, 7.1; N, 9.3. Found: C,74.4; H, 7.1; N, 9.2.

EXAMPLE 26 Preparation of Ethyl3,3-bis(dimethylamino)-2-tri(p-fluorophenyl)borylisocyano-2-propenoate(D-37)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (1.96g, 6.62 mmol) in tetrahydrofuran (6 mL); and (2)3,3-bis(dimethylamino)-2-isocyano-2-propenoate (D-36a) (1.40 g, 6.62mmol) in tetrahydrofuran (6 mL). After the reaction had stirred 1 hourat 0° C., the solvent was evaporated under reduced pressure. The residuewas chromatographed on silica gel, eluting with ethyl acetate to give alight tan solid (2.69 g).

It was recrystallized from ethanol (hot filtration) to give pure D-37(2.23 g, 66%) as a white crystalline solid (mp 150.5°-152.5° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.23 (6H, dd, J=6.4, 8.2), 6.94 (6H, t,J=8.9), 4.22 (2H, q, J=7.1), 2.94 (6H, br s), 2.76 (3H, br s), 1.31 (3H,t, J=7.1). IR (IBr) 1700, 1600, 1565, 1540, 1505 cm⁻¹. FDMS (m/e) 507(M+), 296. λ_(max) CH₂ Cl₂ (ε): 295 (19,300).

Anal. calc'd. for C₂₈ H₂₉ BF₃ N₃ O₂ : C, 66.5; H, 5.8; N, 8.3. Found: C,66.5; H, 5.8; N, 8.2.

EXAMPLE 27 Preparation of Ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-triphenylborylisocyano-2-acetate(D-39) (a) Preparation of Ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-isocyanoacetate (D-39a)

A slurry of 1,3-dimethyl-2-ethoxy-4,5-dihydroimidazoliumtetrafluoroborate (100 mmol as 100% of theory) was prepared as describedby von H. Meerwein, W. Florian, N. Schon, G. Stopp, Liebigs Ann. Chem.641, 1, (1960), using the following materials: (1) boron trifluorideetherate (19.0 g, 134 mmol); (2) epichlorohydrin (9.25 g, 100 mol); and(3) 1,3-dimethylimidazolidin-2-one (11.4 g, 100 mmol).

The anion of ethyl isocyanoacetate was made as follows: To a slurry ofpotassium t-butoxide (11.2 g, 100 mmol) in dry, distilledtetrahydrofuran (80 mL) in a 3-neck 500 mL flask at -78° C. under argonwas added dropwise from an addition funnel a solution of ethylisocyanoacetate (11.3 g, 100 mmol) in dry, distilled tetrahydrofuran (80mL). The anion was allowed to form for 25 min at -78° C., then the flaskwas equipped with an overhead stirrer. The slurry of thetetrafluoroborate salt was added as quickly as possible through a powderfunnel with a stream of argon. The reaction was stirred 15 min at -78°C., then was allowed to warm to ambient temperature and stir overnight.It was then diluted with water (100 mL) and ethyl acetate and filteredthrough celite. The filtrated was transferred to an addition funnel andextracted three times with ethyl acetate. The combined extracts werewashed with water and saturated sodium chloride, dried over sodiumsulfate, and the solvent removed under reduced pressure. The residue (15g) was a black oil containing some solid. When the material was loadedon a silica gel column for flash chromatography with ethyl acetate, thesolid would not dissolve (1.40 g, pure D-39a by TLC and NMR). Thematerial on the column was eluted with ethyl acetate, to give a brownsolid that was a mixture of the product D-39a and the urea startingmaterial.

The material was recrystallized from ethyl acetate to give the product(2.68 g) as a light tan crystalline solid (total yield 4.08 g, 20%). Asmall portion was recrystallizwd from ethyl acetate for analysis andmelting point (mp 102°-103° C.).

¹ H NMR (300 MHz, CDCl₃) δ 4.18 (2H, q, J=7.1), 3.66 (4H, s), 3.02 (6H,s), 1.32 (3H, t, J=7.1). IR (KBr) 1660, 1545 cm⁻¹. FDMS (m/e) 209 (M+).

Anal. calc'd, for C₁₀ H₁₅ N₃ O₂ : C, 57.4; H, 7.2; N, 20.1. Found: C,57.4; H, 7.1; N, 20.0.

(b) Preparation of Product D-39

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) triphenylborane (2.20 g, 9.1mmol) in tetrahydrofuran (20 mL); and (2) ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-isocyanoacetate (D-39a) (1.90g, 9.1 mmol) in tetrahydrofuran (20 mL). After the reaction had stirred1 hour at 0° C., the solvent was evaporated under reduced pressure.

The residue was recrystallized from ethanol (hot filtration) to give (intwo crops) pure D-39 (2.59 g, 63%) as a white crystalline solid (,mp167°-169° C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.36 (6H, d, J=6.9), 7.24 (6H, app t, J=7.2),7.15 (3H, t, J=7.1), 4.23 (2H, q, J=7.1), 3.61 (4H, s), 2.82 (6H, s),1.35 (3H, t, J=7.1). IR (KBr) 1680, 1545 cm⁻¹. FDMS (m/e) 451 (M+), 450.λ_(max) CH₂ Cl₂ (ε): 286 (12,600).

Anal. calc'd, for C₂₈ H₃₀ BN₃ O₂ : C, 74.5; H, 6.7; N, 9.3. Found: C,74.3; H, 6.7; N, 9.3.

EXAMPLE 28 Preparation of Ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-tri(p-fluorophenyl)borylisocyanoacetate(D-40)

The same procedure was employed for the reaction as for Example 1 (D-1),but using the following materials: (1) tris(p-fluorophenyl)borane (2.63g, 8.89 mmol) in tetrahydrofuran (20 mL); and (2) ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-isocyanoacetate (D-39a) (1.86g, 8.89 mmol) in tetrahydrofuran (20 mL). After the reaction had stirred1 hour at 0° C., the solvent was evaporated under reduced pressure.

The residue was recrystallized from ethanol (hot filtration) to givepure D-40 (3.36 g, 75%) as a white crystalline solid (mp 165.5°-167°C.).

¹ H NMR (300 MHz, CDCl₃) δ 7.24 (6H, dd, J=6.4, 8.3), 6.93 (6H, app t,J=8.9), 4.22 (2H, q, J=7.1), 3.67 (4H, s), 2.84 (6H, s), 1.32 (3H, t,J=7.1). IR (KBr) 1680, 1595, 1550, 1500 cm⁻¹. FDMS (m/e) 505 (M+), 504.λ_(max) CH₂ Cl₂ (ε): 280 (12,900).

Anal. calc'd, for C₂₈ H₂₇ BF₃ N₃ O₂ : C, 66.5 H, 5.4; N, 8.3. Found: C,66.2; H, 5.5; N, 8.3.

                                      TABLE II                                    __________________________________________________________________________    Analytical Data for Intermediates*                                                                            Calc'd. For                                                                            Found                                Dye  λ.sub.max nm                                                                ε                                                                             M.P. °C.                                                                     Mol. Formula                                                                          C  H  N  C  H  N                              __________________________________________________________________________    D-1a 443  62,000    134-134.5                                                                         C.sub.16 H.sub.16 N.sub.2 O.sub.2 S                                                   64.0                                                                             5.4                                                                              9.3                                                                              63.9                                                                             5.4                                                                              9.3                            D-3a 347  39,000  168.5-171                                                                           C.sub.14 H.sub.14 N.sub.2 O.sub.2 S                                                   61.3                                                                             5.1                                                                              10.2                                                                             61.7                                                                             5.2                                                                              10.2                           D-5a 509  62,000  163-165                                                                             C.sub.18 H.sub.18 N.sub.2 O.sub.2 S                                                   66.2                                                                             5.6                                                                              8.6                                                                              66.1                                                                             5.6                                                                              8.5                            D-8a 408  72,000    135-136.5                                                                         C.sub.16 H.sub.16 N.sub.2 O.sub.3                                                     67.6                                                                             5.7                                                                              9.9                                                                              67.6                                                                             5.8                                                                              9.8                            D-10a                                                                              490  71,000  154.5-155.5                                                                         C.sub.18 H.sub.18 N.sub.2 O.sub.3                                                     69.7                                                                             5.8                                                                              9.0                                                                              69.5                                                                             5.6                                                                              8.9                            D-16a                                                                              480  42,500  137.5-139                                                                           C.sub.18 H.sub.18 N.sub.2 O.sub.2                                                     73.4                                                                             6.2                                                                              9.5                                                                              73.7                                                                             6.3                                                                              9.5                                 455  39,000                                                              D-19a                                                                              440  112,000 245-250                                                                             C.sub.18 H.sub.19 Cl.sub.2 N.sub.3 O.sub.2                                            56.9                                                                             5.0                                                                              11.1                                                                             56.5                                                                             5.1                                                                              10.8                                422  61,000                                                                             (sh)                                                           D-22a(1)                                                                           391  25,000  184.5-188                                                                           C.sub.16 H.sub.13 NO.sub.2 S.sub.2                                                    60.9                                                                             4.2                                                                              4.4                                                                              60.8                                                                             4.3                                                                              4.4                                 377  21,000                                                              D-22a(2)                                                                           390  25,000  175-177                                                                             C.sub.16 H.sub.13 NO.sub.2 S.sub.2                                                    60.9                                                                             4.2                                                                              4.4                                                                              60.6                                                                             4.2                                                                              4.3                                 377  21,000                                                              D-24a                                                                              536  17,400  150.5-152                                                                           C.sub.24 H.sub.19 NO.sub.3                                                            78.0                                                                             5.2                                                                              3.8                                                                              78.2                                                                             5.3                                                                              3.7                                 504  17,400                                                                   407  15,800                                                                   388  17,100                                                                   309  23,000                                                              D-29a                                                                              470  36,800                                                                             (sh)                                                                               145-145.5                                                                         C.sub.24 H.sub.19 NO.sub.3                                                            78.0                                                                             5.2                                                                              3.8                                                                              78.1                                                                             5.3                                                                              3.7                                 446  40,600                                                              D-31a                                                                              544  35,000  161.5-162.5                                                                         C.sub.18 H.sub.18 N.sub.2 O.sub.2                                                     73.4                                                                             6.2                                                                              9.5                                                                              73.0                                                                             6.1                                                                              9.4                                 510  39,000                                                              D-39a                                                                              483  24,000  102-103                                                                             C.sub.10 H.sub.15 N.sub.3 O.sub.2                                                     57.4                                                                             7.2                                                                              20.1                                                                             57.4                                                                             7.1                                                                              20.0                           __________________________________________________________________________     *All compounds were also characterized by 300 MHz .sup.1 H NMR, IR, and       FDMS.                                                                    

                                      TABLE III                                   __________________________________________________________________________    Analytical and Absorption Data for the Polymethines*                                                       Calc'd. For                                                                            Found                                   Dye                                                                              λ.sub.max nm                                                               ε                                                                          M.P. °C.                                                                      Mol. Formula                                                                            C  H  N  C  H  N                                 __________________________________________________________________________    D-1                                                                              462 87,000                                                                               160-161                                                                            C.sub.34 H.sub.31 BN.sub.2 O.sub.2 S                                                    75.3                                                                             5.8                                                                              5.2                                                                              75.7                                                                             5.9                                                                              5.2                               D-2                                                                              463 86,000                                                                               164-166                                                                            C.sub.34 H.sub.28 BF.sub.3 N.sub.2 O.sub.2 S                                            68.5                                                                             4.7                                                                              4.7                                                                              68.3                                                                             4.9                                                                              4.6                               D-3                                                                              349 46,000                                                                               140-142                                                                            C.sub.32 H.sub.29 BN.sub.2 O.sub.2 S                                                    74.4                                                                             5.7                                                                              5.4                                                                              74.7                                                                             5.8                                                                              5.4                               D-4                                                                              349 46,000                                                                               158-160                                                                            C.sub.32 H.sub.26 BF.sub.3 N.sub.2 O.sub.2 S                                            67.4                                                                             4.6                                                                              4.9                                                                              67.3                                                                             4.8                                                                              4.9                               D-5                                                                              555 112,000                                                                              187-189                                                                            C.sub.36 H.sub.33 BN.sub.2 O.sub.2 S                                                    76.1                                                                             5.9                                                                              4.9                                                                              75.8                                                                             5.8                                                                              5.2                               D-6                                                                              556 118,000                                                                            146.5-147                                                                            C.sub.36 H.sub.30 BF.sub.3 N.sub.2 O.sub.2 S                                            69.5                                                                             4.9                                                                              4.5                                                                              69.2                                                                             5.1                                                                              4.5                               D-8                                                                              424 87,000                                                                               151-151.5                                                                          C.sub.34 H.sub.31 BN.sub.2 O.sub.3                                                      77.6                                                                             5.9                                                                              5.3                                                                              77.5                                                                             5.9                                                                              5.3                               D-9                                                                              425 91,000                                                                             156.5-158                                                                            C.sub.34 H.sub.28 BF.sub.3 N.sub.2 O.sub.3                                              70.4                                                                             4.9                                                                              4.8                                                                              70.1                                                                             4.8                                                                              4.7                               D-10                                                                             520 102,000                                                                              145-148(dec)                                                                       C.sub.36 H.sub.33 BN.sub.2 O.sub.3                                                      78.3                                                                             6.0                                                                              5.1                                                                              78.1                                                                             6.1                                                                              5.0                               D-11                                                                             521 101,000                                                                            167.5-169(dec)                                                                       C.sub.36 H.sub.30 BF.sub.3 N.sub.2 O.sub.3                                              71.3                                                                             5.0                                                                              4.6                                                                              70.9                                                                             5.1                                                                              4.5                               D-16                                                                             509 47,000                                                                               174-175(dec)                                                                       C.sub.36 H.sub.33 BN.sub.2 O.sub.2                                                      80.6                                                                             6.2                                                                              5.2                                                                              80.2                                                                             6.2                                                                              5.2                                  480 57,000                                                                 D-17                                                                             507 48,500                                                                               175-176(dec)                                                                       C.sub.36 H.sub.30 BF.sub.3 N.sub.2 O.sub.3                                              73.2                                                                             5.1                                                                              4.7                                                                              73.2                                                                             5.4                                                                              4.7                                  479 55,000                                                                 D-19                                                                             446 116,000                                                                              178-180(dec)                                                                       C.sub.36 H.sub.34 BCl.sub.2 N.sub.3 O.sub.2                                             69.5                                                                             5.5                                                                              6.8                                                                              69.6                                                                             5.6                                                                              6.9                               D-20                                                                             445 102,000                                                                              144-148(dec)                                                                       C.sub.36 H.sub.31 BCl.sub.2 F.sub.3 N.sub.3 O.sub.2                                     63.9                                                                             4.6                                                                              6.2                                                                              63.8                                                                             4.6                                                                              6.1                               D-22                                                                             406 26,000                                                                               119-121(dec)                                                                       C.sub.34 H.sub.28 BNO.sub.2 S.sub.2                                                     73.2                                                                             5.1                                                                              2.5                                                                              73.1                                                                             5.3                                                                              2.5                               D-23                                                                             406 28,000                                                                               117-127(dec)                                                                       C.sub.34 H.sub.25 BF.sub.3 NO.sub.2 S.sub.2                                             66.8                                                                             4.1                                                                              2.3                                                                              66.8                                                                             4.2                                                                              2.3                               D-24                                                                             544 24,300                                                                             148.5-150                                                                            C.sub.42 H.sub.34 BNO.sub.2                                                             82.5                                                                             5.6                                                                              2.3                                                                              82.7                                                                             5.8                                                                              2.4                                  513 20,900                                                                    391 13,100                                                                    317 20,300                                                                 D-25                                                                             544 25,100                                                                               139-141(dec)                                                                       C.sub.42 H.sub.31 BF.sub.3 NO.sub.3                                                     75.8                                                                             4.7                                                                              2.1                                                                              75.9                                                                             5.0                                                                              2.0                                  409 14,100                                                                    391 13,100                                                                    317 20,700                                                                 D-29                                                                             519 18,800                                                                               117-120(dec)                                                                       C.sub.42 H.sub.34 BNO.sub.3                                                             82.5                                                                             5.6                                                                              2.3                                                                              80.7                                                                             5.9                                                                              2.2                                  492 29,500                                                                    470 25,700                                                                    330  8,000                                                                 D-30                                                                             525 32,200                                                                               114-120(dec)                                                                       C.sub.42 H.sub.31 BF.sub.3 NO.sub.3                                                     75.8                                                                             4.7                                                                              2.1                                                                              75.5                                                                             5.2                                                                              2.3                                  493 48,700                                                                    330 12,800                                                                 D-31                                                                             555 85,000                                                                               168-168.5                                                                          C.sub.36 H.sub.33 BN.sub.2 O.sub.2                                                      80.6                                                                             6.2                                                                              5.2                                                                              80.7                                                                             6.7                                                                              5.1                                  519 53,000                                                                 D-32                                                                             555 90,000                                                                             164.5-166                                                                            C.sub.36 H.sub.30 BF.sub.3 N.sub.2 O.sub.2                                              73.2                                                                             5.1                                                                              4.7                                                                              73.3                                                                             5.4                                                                              4.4                                  519 54,000                                                                 D-33                                                                             294 20,400                                                                               114-116.5                                                                          C.sub.26 H.sub.27 BN.sub.2 O.sub.2                                                      76.1                                                                             6.6                                                                              6.8                                                                              76.3                                                                             6.6                                                                              6.8                               D-34                                                                             293 19,500                                                                             124.5-127.5                                                                          C.sub.26 H.sub.24 BF.sub.3 N.sub.2 O.sub.2                                              67.3                                                                             5.2                                                                              6.0                                                                              67.2                                                                             5.3                                                                              6.0                               D-36                                                                             296 19,200                                                                             141.5-143                                                                            C.sub. 28 H.sub.32 BN.sub.3 O.sub.2                                                     74.2                                                                             7.1                                                                              9.3                                                                              74.4                                                                             7.1                                                                              9.2                               D-37                                                                             295 19,300                                                                             150.5-152.5                                                                          C.sub.28 H.sub.29 BF.sub.3 N.sub.3 O.sub.2                                              66.3                                                                             5.8                                                                              8.3                                                                              66.5                                                                             5.8                                                                              8.2                               D-39                                                                             286 12,600                                                                               167-169                                                                            C.sub.28 H.sub.30 BN.sub.3 O.sub.2                                                      74.5                                                                             6.7                                                                              9.3                                                                              74.3                                                                             6.7                                                                              9.3                               D-40                                                                             280 12,900                                                                             165.5-167                                                                            C.sub.28 H.sub.27 BF.sub.3 N.sub.3 O.sub.2                                              66.5                                                                             5.4                                                                              8.3                                                                              66.2                                                                             5.5                                                                              8.3                               __________________________________________________________________________     *All compounds were also characterized by 300 MHz .sup.1 H NMR, IR, and       FDMS.                                                                    

From Tables II and III it is apparent that close agreement between thecalculated and found elemental content of the compounds was observed.The peak absorption (λ_(max)) of the compounds was measured indichloromethane. The extinction coefficient (ε), in liters/mole-cm wasmeasured in solution at the peak absorption. Several of the dyesexhibited more than one absorption peak, as indicated in the Table II.Most of the compounds were clearly dyes--i.e., they exhibited an anextinction coefficient of greater than 5,000 liters/mole-cm in thewavelength range within the visible spectrum of 400 to 700 nm. All ofthe remaining compounds were ultraviolet absorbers.

EXAMPLES 29 through 33

A series of negative working photoresist compositions PR-1 eachcontaining 0.02 millimole of a different dye being tested as aphotosensitizer were prepared.

PR-1 was formulated as follows:

    ______________________________________                                        2.34    g           Binder A                                                  1.17    g           Monomer A                                                 1.17    g           Monomer B                                                 0.012   g           Inhibitor A                                               0.077   g           Activator A                                               0.02    mmol        Photosensitizer                                           10.32   g           Solvent (Dichloromethane)                                 ______________________________________                                    

Binder A exhibited the following structure ##STR6##

Monomer A exhibited the following structure ##STR7##

Monomer B exhibited the following structure ##STR8##

Inhibitor A exhibited the following structure ##STR9##

Activator A was 1-methoxy-4-phenylpyridinium tetrafluoroborate.

Each of the photoresist compositions was coated on a copper sheet usinga 0.3 mm coating knife and dried for 10 minutes at about 70° C. Atransparent polypropylene cover sheet was then placed over the coating.

Since PR-1 without the photosensitizer coinitiator responds toultraviolet exposures, shorter wavelengths were removed duringexposures, shorter wavelengths were removed during exposure usingfilters. Specifically, wavelengths below the absorption peak of thephotosenitizer dye were removed using a W-2A Wratten® filter capable offiltering 99.9 percent of radiation of less than 400 nm in wavelength.

To determine the degree of effectiveness of the photosensitizer exposureof each coated sample was undertaken through a Kodak T-14® step tablethaving 14 equal increment density steps ranging in density fromessentially zero to 2.1. Three minute exposures were undertaken using aNu-arc FT32L® flip-top platemaker equipped with a 4000 watt pulses Xenonlamp. After exposure the samples were baked for 10 minutes at 70° C. andspray developed for two minutes. Development was undertaken using1,1,1-trichloroethane as a developer. Response was measured in terms ofthe number of stepped exposure areas (steps) in which the photoresistwas retained following exposure. For example, a photoresist sample whichwas retained following exposure and development on 10 steps, but wasabsent from the remaining four steps was assigned a step rating of 10.If partial retention of the photoresist was observed on the eleventhstep, this was indicated by assigning a plus rating--i.e., 10+. On theoter hand, where the photoresist retention was deemed just barelyadequate to merit the step rating, this was indicated by assigning aminus rating--i.e., 10-.

Results with the various dyes are indicated below in Table IV, whichreports the absorption peak of the dye in the coating and the step rangeof response. Activator A exhibited a reduction potential of -0.75 volt,and each of the dye photosensitizers exhibited a reduction potentialless than 0.1 volt more positive than the reduction potential ofActivator A.

When control formulations of PR-1 were prepared varied only by omittingthe dye, so that Activator A was the sole initiator present, performanceof the procedure described above and including the filtering used withthe dyes resulted in no imaging response being observed. This showed theactivator to be ineffective to impart sensitivity to the photoresist inthe blue portion of the spectrum.

The dyes employed as photosensitizers, their maximum absorptionwavelengths (λ_(max)), and the number of steps of retained photoresistafter development are shown in Table IV.

                  TABLE IV                                                        ______________________________________                                        Dye            λ.sub.max (nm)                                                                   Steps                                                ______________________________________                                        D-5            563       10.sup.+                                             D-6            564       10.sup.+                                             D-9            432       5                                                     D-10          529       10.sup.+                                              D-17          486       6                                                    ______________________________________                                    

By comparing the maximum absorption wavelengths of the dyes in solutionin Table III with the maximum absorption wavelengths of the dyes in thephotoresist it is apparent that the maximum absorption wavelength wasbathochromically shifted in the imaging composition. All of the dyes ofthe invention tested in the photoresist composition PR-1 were found tobe useful as photosensitizers. All of these dyes exhibited a reductionpotential more negative than -0.75 volt.

The invention has been described in detail with particular reference topreferreds embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

What is claimed is:
 1. A polymethine dye or ultraviolet absorber of theformula: ##STR10## where Ar is independently in each occurrence anaromatic nucleus containing from 6 to 10 ring carbon atoms;D is anelectron withdrawing group having a cyano, sulfo, or carbonyl group; Eis chosen from the class consisting of(i) a heterocyclic nucleuscomprises of a five or six membered heterocyclic ring containing atleast one heteroatom chosen from the class consisting of nitrogen andchalcogen and (ii) an aminomethine group; L¹ and L² are methine groups;and n is the integer 0, 1, or
 2. 2. A polymethine dye or ultravioletabsorber accordaing to claim 1 wherein n is 1 or
 2. 3. A polymethine dyeor ultraviolet absorber according to claim 2 wherein D is a sulfo group.4. A polymethine dye or ultraviolet absorber according to claim 1wherein D is a carboxylic ester group.
 5. A polymethine dye orultraviolet absorber according to claim 1 wherein E is comprised of anazolinylidene or azinylidene heterocyclic ring.
 6. A polymethine dye orultraviolet absorber according to claim 1 wherein E is an aminomethinegroup, the amino moiety of which is derived from a secondary amine.
 7. Apolymethine dye or ultraviolet absorber according to claim 6, whereinthe cyclic secondary amine is chosen from the group consisting of apyrrolidine, 3-pyrroline, piperidine, piperazine, morpholine,1,2,3,4-tetrahydroquinoline, decahydroquinoline,3-azabicyclo[3,2,2]nonane, indoline, azetidine, and hexahydroazepine. 8.A polymethine dye or ultraviolet absorber of the formula: ##STR11##where D is a --C.tbd.N, --S(O)₂ OR, --C(O)R, or --C(O)OR;E representsthe atoms completing an aromatic heterocyclic nucleus comprised of anazolinylidene, azinylidene, pyranylidene, thiopyranylidene,selenapyranylidene, tellurapyranylidene, or dithiolylidene ring; n isthe integer 0, 1, or 2; and R is chosen from the class consisting ofalkyl, alkenyl, alkynyl, aryl, alkaryl, and aralkyl, wherein said alkyl,alkenyl, and alkynyl moieties contain from 1 to 15 carbon atoms and saidaryl moieties contain from 6 to 10 carbon atoms.
 9. A polymethine dye orultraviolet absorber according to claim 8 wherein the azolinylidene ischosen from the class consisting of benzothiazolinylidene,benzoxazolinylidene, quinolinylidene, and benzimadazolinylidene.
 10. Apolymethine dye or ultraviolet absorber of the formula: ##STR12## whereAr is independently in each occurrence an aromatic nucleus containingfrom 6 to 10 ring carbon atoms;D is an electron withdrawing group havinga cyano, sulfo, or carbonyl group; G², G³, G⁴, and G⁵ are independentlyin each occurrence chosen from the class consisting of alkyl, alkenyl,alkynyl, aryl, alkaryl, and aralkyl, wherein said alkyl, alkenyl, andalkynyl moieties contain from 1 to 15 carbon atoms and said arylmoieties contain from 6 to 10 carbon atoms, G² and G³ together completea cyclic secondary amine, G⁴ and G⁵ together complete a cyclic secondaryamine, or G² and G⁴ together complete a 5 or 6 membered ring; L¹ and L²are methine groups; and n is the integer 0, 1, or
 2. 11. A polymethinedye or ultraviolet absorber according to claim 10 whereinn is 0 and D isa --C.tbd.N, --S(O)₂ OR, --C(O)R, or --C(O)OR; and R is independently ineach occurrence chosen from the class consisting of alkyl, alkenyl,alkynyl, aryl, alkaryl, and aralkyl, wherein said alkyl, alkenyl, andalkynyl moieties contain from 1 to 15 carbon atoms and said arylmoieties contain from 6 to 10 carbon atoms.
 12. A polymethine dye orultraviolet absorber according to claim 11 wherein D is --C(O)OR and Ris independently in each occurrence alkyl of from 1 to 6 carbon atoms oraryl of 6 to 10 carbon atoms.
 13. A polymethine dye or ultravioletabsorber according to claim 10 wherein at least one of G² and G³together or G⁴ and G⁵ together form a cyclic secondary amine chosen fromthe group consisting of pyrrolidine, 3-pyrroline, piperidine, piperazine(e.g., 4-methylpiperazine and 4-phenylpiperazine), morpholine,1,2,3,4-tetrahydroquinoline, decahydroquinoline,3-azabicyclo[3,2,2]nonane, indoline, azetidine, and hexahydroazepine.14. A polymethine dye or ultraviolet absorber selected from the groupconsisting ofethyl4-(3-ethyl-2-benzothiazolinylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(3-ethyl-2-benzothiazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl2-(3-ethyl-2-benzothiazolinylidene)-2-tritriphenylborylisocyanoacetate;ethyl2-(3-ethyl-2-benzothiazolinylidene)-2-tritri(p-fluorophenyl)borylisocyanoacetate;ethyl6-(3-ethyl-2-benzothiazolinylidene)-2-tritriphenylborylisocyano-2,4-hexadienoate;ethyl6-(3-ethyl-2-benzothiazolinylidene)-2-tritri(p-fluorophenyl)borylisocyano-2,4-hexadienoate;3-ethyl-2-(1-triphenylborylisocyano-1-phenylsulfonyl-1-propen-3-ylidene)benzothiazoline;ethyl4-(3-ethyl-2-benzoxazolinylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(3-ethyl-2-benzoxazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl6-(3-ethyl-2-benzoxazolinylidene)-2-triphenylborylisocyano-2,4-hexadienoate;ethyl6-(3-ethyl-2-benzoxazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2,4-hexadienoate;2-[1-Cyano-1-tri(p-fluorophenyl)borylisocyano-1-propen-3-ylidene]-3-ethylbenzoxazoline;ethyl4-(3-ethyl-2-selenazolinylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(3-ethyl-2-benzoselenazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;methyl2-(3-ethyl-2-benzotellurazolinylidene)-2-triphenylborylisocyanoacetate;ethyl4-(1-ethyl-2-quinolinylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(1-ethyl-2-quinolinylidene)-2-tri-(p-fluorophenyl)borylisocyano-2-butenoate;methyl4-(1-methyl-2-pyridylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoateethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(5,6-dichloro-1,3-diethyl-2-benzimidazolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl4-[3,3-dimethyl-1-ethyl-2(3H)-indolylidene]-2-triphenylborylisocyano-2-butenoate;ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene)-2-triphenylborylisocyanoacetate;ethyl2-(4,5-dihydronaphtho[1,2-d]-1,3-dithiol-2-ylidene)-2-tri(p-fluorophenyl)borylisocyanoacetate;ethyl4-(4,6-diphenyl-2-pyranylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(4,6-diphenyl-2-pyranylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl4-(2,6-di-t-butyl-4-selenapyranylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl2-(2,6-diphenyl-4-tellurapyranylidene)-2-triphenylborylisocyanoacetate;ethyl4-(2-phenyl-4-benzothiapyranylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl4-(2,6-diphenyl-4-pyranylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(2,6-diphenyl-4-pyranylidene)-2-trifluorophenylborylisocyano-2-butenoate;ethyl4-(1-ethyl-4-quinolinylidene)-2-triphenylborylisocyano-2-butenoate;ethyl4-(1-ethyl-4-quinolinylidene)-2-tri(p-fluorophenyl)borylisocyano-2-butenoate;ethyl 3-dimethylamino-2-triphenylborylisocyano-2-propenoate; ethyl3-dimethylamino-2-tri(p-fluorophenyl)borylisocyano-2-propenoate; methyl3-dimethylamino-2-tri(p-tolyl)borylisocyano-2-propenoate ethyl3,3-bis(dimethylamino)-2-triphenylborylisocyano-2-propenoate; ethyl3,3-bis(dimethylamino)-2-tri(p-fluorophenyl)borylisocyano-2-propenoate;methyl 5-dimethylamino-2-triphenylborylisocyano-2,4-pentadienoate ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-triphenylborylisocyanoacetate;and ethyl2-(1,3-dimethyl-2-imidazolidinylidene)-2-tri(p-fluorophenyl)borylisocyanoacetate.15. An imaging composition comprised of an ultraviolet responsiveimaging material and a photosensitizer for rendering said imagingmaterial responsive to the visible spectrumcharacterized in that saidphotosensitizer is a polymethine dye according to claim
 1. 16. A silverhalide photographic element comprised ofa support, one or morehydrophilic colloid layers on said support including at least oneradiation-sensitive silver halide emulsion layer, and a polymethine dyeor ultraviolet absorber according to claim
 1. 17. A photographic imagingsystem comprised ofan imaging dye or precursor thereof, a hardenableorganic component containing ethylenic unsaturation sites and capable ofimagewise modulating mobility of said dye or dye precursor as a functionof addition at the sites of ethylenic unsaturation, and coinitiators forethylenic addition comprised of an azinium salt activator and apolymethine dye according to claim
 1. 18. A negative working photoresistcomprised ofan organic film forming component containing ethylenicunsaturation and capable of selective immobilization by addition at thesite of ethylenic unsaturation and coinitiators for ethylenic additioncomprised of an azinium salt activator and a polymethine dye accordingto claim 1, said dye exhibiting a reduction potential which in relationto that of said azinium salt activator is at most 0.1 volt morepositive.